There is nothing wrong with “the sinner’s prayer”, and there is nothing wrong wtih praying with others. The absolute best prayer is the Mass, and praying the Scriptures through the liturgy. Yes, of course you can invite people to come to RCIA.
Not sure exactly what you are asking here. Of course it is important to repent and put faith in Jesus verbally. This is what we do at every Mass.
That is different for different people. All receive the HS in baptism. Some never depart from Him, and live a life of obedience in faith. Some receive the HS in baptism, then wander away from the faith into which they were baptized, and have a powerful conversion experience when returning.
Some recieve the HS before they are baptized, as Cornelius did in Acts. ch. 10.
Yes, yes, and yes.
Protestants make what Catholics call an “act of faith”, and God honors their desire for union with Him.God is not bound by the Sacraments. He created them so that we could know and depend upon His channels of grace,
but He pours out his Grace wherever and whenever He wants.
Yes, and we Catholics call that particular grace 'actual grace". And God is always there beside us ready ,as many Prostestants would say, to convict our hearts of the sin we are committing and drawing us to him to repent and to accept and recieve redemption from Christ. The beginning of conversion for many.
Peace, Carlan