Is it possible that replacing the two button steering wheel with the multi button wheel will enable cruise control? IE: are the wires, contacts, software already in the car? I suppose the same question would also involve remote audio controls. Any knowledge?
Yes it is possible - there is a retrofit kit available. There are a few extras required to be fitted, mainly a wiring loom extra, and a clutch switch. It is my understanding that the kit (part no 65 71 0 029 494) works on most mini's EXCEPT those with SAT NAV already installed (apparently it's to do with the wiring available - and yes you can get factory fitted SAT NAV and MFSW - but not as an retro fit option.)
Programming is also required so at (least) some part of the install has to be done by a auth BMW dealer. The PDF of the install manual is available (I think) from the Techincal->DIY etc part of this web site.