I'll leave the plastic/glass debate to others (I'm a glass person,
myself).

It sounds like your main concern is not throwing money away (big
shocker there, huh? ;-) Everyone has to start their knowledge base
somewhere, and here is where yours begins. (welcome to the world of
large aquaria, by the way). THE best way to not throw money away in
this hobby is by READING. (And believe me, it's very easy to throw
money away at an alarming rate when you own a large tank!) The best
place to start (and finish, for that matter) is the forums at
www.reefland.com and www.reefs.org. Spend at least a couple weeks
(yes, weeks) reading over the various sections of the forums. Read the
FAQ's and then, after you get a feel for what you're getting into,
post whatever questions you may have to the forums. You'll find the
bredth and depth of the knowledge there almost limitless. Best of all,
it's all catagorized and searchable. (Do a search at reefland.com for
how to move a 180 gallon tank (with livestock) 850 miles and you'll
find my article).

I can tell by the questions that you're asking that you are at the
very beginning of what will be a long voyage into large tanking. You
will soon be learning about overflows (not what you're
thinking...overflows are a good thing!), sumps, refugiums, metal
halide, T-5's, VHO's, protein skimmers and submersible heaters. Do
some reading on ALL those subjects....take your time, enjoy the
ride...this is supposed to be fun, remember? (read extra about protein
skimming)

To answer your questions...leave your 29 set up and running. Leave all
your equipment on there; it's of little use on a large tank. Voila!
You now have a quarantine tank! (You don't want a single sick fish
infecting a hundred gallons worth of healthy fish). Come to think of
it, add quarantine tank to the list of study material above.

Have fun; don't rush. Nothing good happens fast in this hobby.

Blue Skies,
JJ