hey, what's up? 400w is good, but PP is right...HPS will allow more stretching at young age,,,some cfl's 1" above seedlings will allow them to root and fill out
before you set them under an HID, but it won't be that bad if you just use the 400w...imho
You need a small fan moving air inside the cabinet; to keep the canopy cool and to exercise your plants, this will allow them to grow strong stalks
flat white paint is alot better than alfoil and mix your soil/perlite 50/50...
...hope this helps...are you ready for all the work?.peace