Now on zippering. As was noted this is affected by how closely your belayer stands to the base of the route. But what is not as commonly thought of is that the lower your first piece is, the more likely it is to zipper.
wanna test this? put a piece in two feet off the ground and start leading. The rope will make a right angle bend through this first piece pretty much no matter where your belayer stands in relation to the crag. If you fall, this piece will have a huge outwards and upwards pull on it and will probably zipper.
So if you want to avoid your gear zippering, avoid a low first piece. Lots of people get this seriously wrong.