T8 or T12 are older than T5. They are not much effective as T5. But when you're choosing, look for High Output T5. standart T5 don't have that much lumen.
You can fit them in length to your grow-room, or you can use PL-L as well in width. They are more compact in length and near same lumen output.
If you use only 2x250w CFL you got 2 sources for light. Plants will try to reach those sources. If you spread the light equally, All plants will share same light output, they'll be more happy.
Here I wrote a while ago about: http://boards.cannabis.com/closet-ca...ml#post2167239

And, it doesn't really matter actually, you can post here or there. Better do in right room and ask one time. When you need more or different answers to same question, you can just come to your thread and send another post to keep it up