For that price the t-rex is supposed to be a good frame. I've never ridden one but i've heard good things about them. However, for only 30 quid more you could get something like a echo or a zoo etc....
Shimano don't make isis bottom brackets, they make something similar however it is only compatable with shimano cranks. Many people use fsa or truvativ which would probably work out cheaper.
My theory: Piss smells of sugar puffs in the morning when it is quite concentrated. You also tend to eat sugar puffs for breakfast (i.e. in the morning). So it could just be a coincidence
I learn from watching vids of other riders doing the moves. However, the biggest help is watching other riders and them explaining how to do the move (namely mike, dave, and cj). It's also good to watch Luke Draisey to see how not to do things
I used to have a base ta20 (don't know if that's the same as a t20????) and my cousin has a t-bird and to be honest there was hardly any difference in how they rode. So i'd say just go for which ever you prefer the look of etc
In no particular order: Audioslave (self titled) Deftones (self titled) Foo Fighters - The Colour And The Shape Interpol - Antics Maximo Park - A Certain Trigger Muse - Origin Of Symmetry Queens Of The Stone Age - Lullabies To Paralyze Radiohead - Ok Computer Rage Against The Machine - The Battle Of Los Angeles System Of A Down - Steal This Album
The fixed hub has threads on it for you to either attach a fixed cog or a freewheel, whereas the freehub version is like a profile or a king with a built in freewheel