a lot of your questions depend on the species. tegus in general can range from 18"-5'. Chilean Dwarf Tegu being the smallest and Argentine BW or Red being the largest. ill go thru all the species
Argentine Black and White Tegu- they range from 3½ft to 5ft. they need a large enclosure. Taz (my Arg BW) lives in a 8x4x4 cage. they can be housed in smaller than that. such as a 6x3x3.
i keep his humidity level at around 60-70% and i soak him about 5mins everyday. at a SPOT in the cage it is 135F and goes down to 70F. keep in mind i said spot. 6inches away its 110F. 1ft away its 90F. as babies they should eat mainly crickets and superworms. Taz now eats chicks and rats. he is EXTREMELY tame. he has ALWAYS been like this. he is awesome to have he was my first lizard and would recommend this species to anyone looking for a large "nice" lizard. though i searched for about 8months on the internet for everything i could find on them.
Argentine Red- they are pretty much the same to the Black and White Argentines. there are some differences in keeping and such though. they do eat more fruit, and they need higher humidity. and obviously from the name are Red, and not black and white. Males are a brick red and females are a brownish red.
Colombian/Gold Tegu- these are smaller ranging in sizes from 2'-3½'. in some cases 4'. they are typically more aggressive. though i believe they are this way because most are Wild Caught and not Captive Bred like the Argentines. if you decide on this species try your hardest for a CB and you will be much happier. they CAN be tamed as much as the Argentines. and they are strictly meat eaters.
Blue Tegu- they are more in size of a Colombian tegu, but typically have good attitudes as the Argentines do.
Chilean Dwarf Tegu- these range in size from 18"- 2½' they are very active and like it drier than the other tegus. they attitudes range from skittish/aggressive to very tame. they have some really cool markings.
now that does it for tegus u would normally see in the pet trade. there are other such as the Water Tegu etc etc
if you want an Argentine BlackWhite Tegu i would HIGHLY!!!! recommend Agama International. that is where i got Taz.
for Argentine Reds i would say Ron St Pierre now is probably the best. though they are sold out for this year. Next year Agama International will have baby Reds and i would buy from them.
Blue Tegus i would go to Ron St Pierre, they seem to be the best for blue tegus.
for Colombian/Gold and Chilean Dwarf Tegus there is no "best" breeders for them as they normally are WC.
i think that about does it. any more questions just ask
here are some links
Agama International www.agamainternational.com
Ron St Pierre www.bluetegu.com
im sure some ppl will disagree with some things iv said here in keeping them. oh well. im sure i left some things out. plus its late 