1) zaps are payments we sent to each other. It uses bitcoin lightning that's were the term comes from, the unit is sats, so you can say I zapped 21 sats. You need a Lightning wallet that has an lnaddress, it's like an email address, then you can put that address in you profile, there is a field for it. 

2)Best way is to just check what other people are using, beware some of the might be paid, and you don't need too many, 4/5 good ones are enough. You can also use blasters that will fire your notes to many relays.