Assuming you mean that the sanctuary will be used, and not the altar itself, one would have to define “skit”. Something along the lines of a morality play or a pastorella, though, would not be inappropriate, even though these sometimes include farcical or comical elements. It isn’t a sin to laugh in church, as long as the cause of the laughter also conforms the soul towards grace.
It isn’t out of place to use a sanctuary as a performance space, particularly when the subject matter is religious and good acoustic quality is necessary, but suffice it to say that the entire performance would have to be reviewed in detail by the pastor. I don’t know of a pastor that would not require this, except perhaps if the production was under the supervision of someone whose judgement he thinks is beyond question. In the end, though, it is the pastor’s responsibility to defend the sanctuary against improper use.
If a table is needed for the performance, though, it may not be the altar, nor a table that might be mistaken for the altar. It must clearly be just a table, for the sake of avoiding scandal. The altar itself should either be behind a screen or continue to be given the proper respect it would always merit, except whenever the performers were clearly required by “being in character” to do otherwise. That is, the performers’ awareness and respect for the altar should not be in question, even though, for instance, some of them would be talking and acting the parts of vices or evil spirits in something like a pastorella, or even the good characters might be in an imaginary setting that doesn’t have an altar in it, that kind of thing. That’s OK: everyone knows what that’s about.
I don’t know if any documents require it, but IMHO for the sake of not giving scandal the Blessed Sacrament should be removed to another chapel. I have even seen some churches go so far as to put drapes in front of the main crucifix when the church wasn’t being used for a liturgy, office, or prayer of some kind. (I could see a pastor taking a different stance, if the topic of the performance was clearly catechetical in nature, though.)
It is OK to have secular music, if the music is not profane, particularly if it is instrumental and if it is not bombastic in tone or clearly reminiscent of profane tunes.