is it possible to make my system run as a wifi range extender/repeater, whilst still having access to the network itself? does this require 2 wifi adapters?

I think that's possible. Your unit shall be required to have another wireless
network adapter for the broadcast extension and an available processor for
the extension processing. (i just don't know which software to use,
i'll check that out and be back here)

Ok, now softwares available are in packages with various Linux OS's distros.

Now, I am hoping we run a virtual machine here. The idea is to run an operating system with the usual router functionality while
using a different mac from a second nic. And yet with our particular requirement (on extending wireless reach of the network),
we hope to get an OS has such router feature.

(Otherelse - somebody "do the codes".)

Btw, I also remember an access in the form of allowing other computers to "Connect from this computer". Definitely that will slow resources down.
For being paranoid, I never tried this ever since though...