Tank Repair

I've got a 58 gal tank with a bottom that is toast. I've got a

couple questions on how to replace the durn thing.

1) How or what do you use to remove the trim around the bottom?

And what do you use to resticky it?

2) Do the four sides sit/rest upon the bottom? Or does the bottom

rest inside the four sides?

3) Is 100% clear silicone sealant OK? Or does it have to be aquarium

grade silicone sealant?

4) What's the best way to spread the silicone into a nice smooth

surface? And how far out should it go?

Any answers appreciated.