Well, their 2nd, 3rd, and 5th observations in the letter restate what’s said in 5 documents. Here are the referenced quotes (
emphases mine):
Ecclesia de Mysterio 6 §2
To promote the proper identity (of various roles) in this area, those abuses which are contrary to the provisions of canon 907 are to be eradicated. In eucharistic celebrations deacons and non-ordained members of the faithful may not pronounce prayers—e.g. especially the eucharistic prayer, with its concluding doxology—or any other parts of the liturgy reserved to the celebrant priest. Neither may deacons or non-ordained members of the faithful use
gestures or actions which are proper to the same priest celebrant. It is a grave abuse for any member of the non-ordained faithful to “quasi preside” at the Mass while leaving only that minimal participation to the priest which is necessary to secure validity.
…]
Every effort must be made to avoid even the appearance of confusion which can spring from anomalous liturgical practices. As the sacred ministers are obliged to wear all of the prescribed liturgical vestments so too the non-ordained faithful may not assume that which is not proper to them.
To avoid any confusion between sacramental liturgical acts presided over by a priest or deacon, and other acts which the non-ordained faithful may lead, it is always necessary to use
clearly distinct ceremonials, especially for the latter.
Codex Iuris Canonici 1169, §2:
Any priest can impart blessings, except for those reserved to the Roman Pontiff or to Bishops.
Benedictiones, exceptis iis quæ Romano Pontifici aut Episcopis reservantur, impertire potest quilibet presbyter.
Familiaris Consortio 84:
Daily experience unfortunately shows that people who have obtained a divorce usually intend to enter into a new union, obviously not with a Catholic religious ceremony. Since this is an evil that, like the others, is affecting more and more Catholics as well, the problem must be faced with resolution and without delay. The Synod Fathers studied it expressly. The Church, which was set up to lead to salvation all people and especially the baptized, cannot abandon to their own devices those who have been previously bound by sacramental marriage and who have attempted a second marriage. The Church will therefore make untiring efforts to put at their disposal her means of salvation.
…]
However, the Church reaffirms her practice, which is based upon Sacred Scripture, of not admitting to Eucharistic Communion divorced persons who have remarried. They are unable to be admitted thereto from the fact that their state and condition of life objectively contradict that union of love between Christ and the Church which is signified and effected by the Eucharist. Besides this, there is another special pastoral reason: if these people were admitted to the Eucharist, the faithful would be led into error and confusion regarding the Church’s teaching about the indissolubility of marriage.
Reconciliation in the sacrament of Penance which would open the way to the Eucharist, can only be granted to those who, repenting of having broken the sign of the Covenant and of fidelity to Christ, are sincerely ready to undertake a way of life that is no longer in contradiction to the indissolubility of marriage. This means, in practice, that when, for serious reasons, such as for example the children’s upbringing, a man and a woman cannot satisfy the obligation to separate, they “take on themselves the duty to live in complete continence, that is, by abstinence from the acts proper to married couples.”
Similarly, the respect due to the sacrament of Matrimony, to the couples themselves and their families, and also to the community of the faithful,
forbids any pastor, for whatever reason or pretext even of a pastoral nature, to perform ceremonies of
any kind for divorced people who remarry. Such ceremonies would give the impression of the celebration of a new sacramentally valid marriage, and would thus lead people into error concerning the indissolubility of a validly contracted marriage.
By acting in this way, the Church professes her own fidelity to Christ and to His truth. At the same time she shows motherly concern for these children of hers, especially those who, through no fault of their own, have been abandoned by their legitimate partner.
With firm confidence she believes that those who have rejected the Lord’s command and are still living in this state will be able to obtain from God the grace of conversion and salvation, provided that they have persevered in prayer, penance and charity.
Cotidianum rerum experimentum pro dolor docet eum qui divortium fecerit, plerumque animo intendere novam transire ad convivendi societatem, sine ritu religioso catholicorum, ut patet. Cum de malo agatur, quod, sicut et alia, latius usque inficiat etiam greges catholicos, haec difficultas est cum cura et sine ulla mora omnino aggredienda. Synodi Patres eam data opera investigaverunt. Nam Ecclesia, idcirco instituta ut ad salutem omnes homines imprimisque baptizatos perduceret, non potest sibimet ipsis illos derelinquere, qui — iam sacramentali vinculo matrimonii coniuncti — transire conati sunt ad nuptias novas. Nitetur propterea neque umquam defessa curabit Ecclesia ut iis praesto sint salutis instrumenta.
…]
Nihilominus Ecclesia inculcat consuetudinem suam, in Sacris ipsis Litteris innixam, non admittendi ad eucharisticam communion em fideles, qui post divortium factum novas nuptias inierunt. Ipsi namque impediunt ne admittantur, cum status eorum et condicio vitae obiective dissideant ab illa amoris coniunctione inter Christum et Ecclesiam, quae Eucharistia significatur atque peragitur. Restat praeterea alia peculiaris ratio pastoralis: si homines illi ad Eucharistiam admitterentur, in errorem turbationemque inducerentur tideles de Ecclesiae doctrina super indissolubilitate matrimonii.
Porro reconciliatio in sacramento pænitentiæ—quae ad Eucharistiae sacramentum aperit viam—illis unis concedi potest, qui dolentes quod signum violaverint Foederis et fidelitatis Christi, sincere parati sunt vitae formam iam non amplius adversam matrimonii indissolubitati suscipere. Hoc poscit rever a ut, quoties vir ac mulier gravibus de causis—verbi gratia, ob liberorum educationem—non valeant necessitati separationis satisfacere, « officium in se suscipiant omnino continenter vivendi, scilicet se abstinendi ab aetibus, qui solis coniugibus competunt ».
Observantia similiter erga matrimonii sacramentum, tum etiam erga coniuges eorumque familiares necnon erg a ipsam fidelium communitatem, vetat quemlibet pastorem ullam propter causam vel praetextum etiam pastoralem ne pro divortio digressis, qui novas nuptias inierunt, ritus cuiusvis generis faciant; hi enim ostenderent novas nuptias sacramentales validas celebrari ac proinde errorem inicerent de indissolubilitate prioris matrimonii valide contracti.
Hoc quidem pacto agens, Ecclesia profitetur fidelitatem suam in Christum eiusque veritatem; simul vero materno affectu se gerit erga hos filios suos, potissimum eos qui nulla propria intercedente culpa a proprio derelicti sunt legitimo coniuge.
Firma insuper cum fiducia Ecclesia credit quotquot a mandato Domini recesserint in eoque etiamnunc statu vivant, a Deo gratiam conversionis ac salutis assequi posse, si in precatione, paenitentia, caritate perseveraverint.
Codex Iuris Canonici 915:
Those upon whom the penalty of excommunication or interdict has been imposed or declared, and others who obstinately persist in manifest grave sin, are not to be admitted to holy communion.
Ad sacram communionem ne admittantur excommunicati et interdicti post irrogationem vel declarationem poenae aliique in manifesto gravi peccato obstinate perseverantes.
De Benedictionibus isn’t available on the Internet.