"Am I right in thinking that Real Tracks can also be transposed into any key..?"

Yes ... you key in the 'original chords' first then you simply change the key to whatever you need and BIAB/RB does the work.

I audition different keys until my voice can handle the the whole song range.

It is AMAZINGLY easy.

I'm doing allright for Country Trash ....

I used to care, but things have changed (Bob Dylan)

BIAB 2022W + RB
M-Audio FastTrack C600, Rode NT2-A
Digitech VoiceLive 4

Epiphone Sheraton, Ibanez 12str, Washburn 6str, Cort 6Str Nylon
Yanagisawa Tenor Sax