1) I would check into some vaccum caps, bought at any auto parts store or Lowes and Home dePot.
2) For 10 gal mix you would need 10 tsp of GB (50 ml) and 20 tsp of BB (100ml)
3) First start of soaking new Tron PH is probably high 7's or so. 5.8 would be the magic number you want to get to and that is what you want your soaking water at, 5.8
4) Yes rez at 68 is great. Have you used these lights before?? You might be surprized how much heat they put out. What size area are we talking about??