should be no ammonia if fish in the tank, and not matter if there are not. as for the straight answer you are looking for I have no ideal. and as a FYI PH is not something you want mess with unless you really know what you are doing and have a reason. most fish do not require it to be messed with.
No. Neutral ph is 7. Ammonia is a base so it well raise the ph (acids lower ph, bases raise it). As pops said, ammonia is bad for fish so you should be doing everything possible to remove it from your tank.