I've done a little bit of tree tapping and no I don't believe the side you tap on makes a difference but I could be wrong. Usually one side will be better simply because the ground is flatter to place the bucket because the bucket can tip over and all your sap can spill out (I know from experience lol). But I think the size diameter of the tree makes a difference, and most importantly the size of the canopy. In other words how many leaves and branches it has. Also, be sure to look out for tree that have a lot of dead branches up top. Avoid using those. You want to look for healthy trees with broad canopies and lots of buds. Those will be your biggest producers.
25-50 ballpark. Depends on sugar content. For a few trees you may want to place sap in a jug, maple empty milk carton and place in freezer until you have enough to boil. My son does this for two taps. Works for him. Like trapping have fun.
I have never done this, but do have a couple of good sized maples in my yard...how many trees/taps would one need to get enough sap to make a gallon of syrup, roughly?
Depending on sugar content about 40 gallons of sap to one gallon of syrup. If you have sugar maples you'll be closer to that ratio. I've had friends that do sap for themselves and it's not hard to get 40 gallons of sap with a handful of taps, when it's running good buckets can fill fast.