I have never grown with terra vega but I will try to help. I really could use a good spankin
3) Basically if the ph is between 6-6.8 it should be fine. I would check my soil and my water just to make sure.
1) As far as ppm I try to stay around 800 ppm for growth and 1200 for flowering. I can figure out the ec once I go to my other place and check my little graph. You need to take into consideration of nutrients that may be in the soil too. I have no clue what terravega is so I dont have a clue. Usually soil with no nutes is easier to work with.
2) As far as what to expect. That is determined by size, space, lumens, nutes, air and prolly the most important would be strain. If you looked at my setup and the size and space I use... I usually get around an oz per plant. I could get more if I grow them bigger and spaced them out some. But I like the plant to concentrate on making one bud instead of lots of smaller buds.
4) I cut any big fan leaf that blocks light from a bud. Dont cut them all off but if you think its blocking light from a potential bud then cut it. I have double harvested once. I basically cut all the top buds that looked ripe and left the lower buds to mature up some. Left them for about another month till they looked ripe too. I am making my plants shorter now so the buds are ripe the first time around usually now. So I dont do that anymore.
5) I dont know this for a fact but I would say too much of anything is not good. I just let my co2 generator run when the lights are on. I have no clue how much it produces. I just run the stupid thing.
6) Usually it grows double the size of what it was when you changed to the 12/12 cycle.
7) This is a must. I dont understand why you would take an a/c out of a car but ok. A nice window unit can be picked up for fairly cheap too. Try to stay below 85*f.