good job going with LST, you will be happier in the long run. bloom nutrients? there are tons of different nutes out there. most will probably say go with the Fox Farm Trio.

and in a cab the size of yours, and it looks like its made out of cardboard(correct me if im wrong), HPS would just be stupid. Add more CFL's if you need more light. get some "Y" adapters and throw in twice the amount of bulbs you have now.