You're asking two questions here. I'll answer the first one, but the second question is so big that I'm just going to answer it in a general way.
The best way to have a chorus-like effect would be for you and your friend to sing the same part again and again until you have what sounds like a whole chorus singing the part. You can even position the mic in different parts of the room when you do this, cuz it will produce a slightly different sound on each take.
A lazy way to get a chorus-like sound out of a few vocal tracks would be to copy each of the vocal tracks you've recorded - make a clone of each track. Make a few clones of each track. Then make each of the clones sound different from the others by putting different EQ settings and effects on each one. Pan them apart from each other.
The 'sequence to follow after you record a track' is called mixing. There are different ways to go about it, but here's a tried and true reliable sequence: do the EQ for each track; compress anything that needs it, but don't touch tracks that don't need it; apply reverb to the tracks that you want reverb on.
