Would the baptism be during Mass or held separately?
Either way, the Priest will direct the proceedings so it should be easy to follow. If you’re comfortable with it, upon entering the Nave it is customary to look for the tabernacle and genuflect. Which is normally done directly before entering the pew where you’ll be sitting.
Other than that, what might be your specific questions?
It actually depends on the parish. Most parishes baptise during a regular Sunday Mass. If that’s the case, there will be an opening hymn and prayer, followed by some readings from scripture, followed by a homily, followed by the Baptism, and finally followed by the Eucharist. Unless you are asked to be a witness, you won’t have to do anything but watch. If you want to follow along with the Mass, you can often find a missal in the pew, which has the readings and responses. If you don’t feel comfortable saying the Mass, it would be fine for you to watch respectfully. Obviously, you should not go up to recieve the Eucharist. Unless the priest specifically invites you to come up for a blessing at the time, I would remain in the pew. Some parishes have Baptisms at a seperate time outside of Mass.
Well first the priest makes sure everyone shows their secret Catholic decoder ring, then…
Assuming you aren’t one of godparents there really isn’t much you have to do. The priest will have the parents, godparents, and child gather around the baptismal font, he will then read the baptismal ceremony from a pamphlet, at some point he will ask the p’s and gp’s some questions, they’ll respond, then he’ll baptize the child. I forget if there is a portion for non-p and gp Catholics at the baptism. If there is, you (as a non-Catholic) just don’t take part in that portion. If you are one of the godparents, I suggest you get with the priest ahead of time for better guidence.
After the homily, there will then be the baptism. Unless it’s a private baptism, this is the usual.
There’s no need to go up for a blessing at Communion, and technically it isn’t allowed either. This is a great, holy, and dramatic time during the most Holy Sacrifice, and it’s for receiving Our Lord. A more appropriate time would be after Mass