1) If you made the whole thing out of silnylon, which is non-breatheable, you'd have LOTS of condensation - so not a good idea.
2) you can buy the Firstlight poles form BD. You can also get poles from Quest outfitters, or go carbon from Fibraplex.
3)You'd need zippers, webbing, velcro for the interior pole attachments, some heavier fabric to reinforce the corners of the floor where the poles sit.

When you get all the bits and pieces added in, you'll find the cost a little higher than you're thinking - especially since you'll need some waterproof/breatheable fabric for the roof portion in place of the silnylon. If you like that tent, I'll bet you can find a used one that won't cost much if any more than the cost of all the materials. To me, though, it doesn't seem like a good AT tent.