I have no idea about this - I've got three separate computers jacked into a hardware router sharing a net connection with lots of wires all over the place.
Networking is not my strong suit and wireless gives me the willies. You need to install the gcc package and apparently a lot of other stuff. What exactly did you install? It might be better to install everything on your first system and then you can learn what you can do without as time goes on. But you can't do without gcc. (It's possible it is installed and there's just another problem, but I doubt it.) Once you do that, the best I can say is
gcc -v (or just look at what you installed, probably 3.3.4)
pick the zip (probably RTL8180_24x_RH90.zip)
But why is it a zip, anyway? For Linux they should distribute tars. Anyway... you can handle zips, so it's not an issue.
(1)$EDITOR Makefile
As far as modifying them, that's easy. To *what*, I haven't a clue. Maybe it has defaults and those will do.
(2)No clue
(3)Yes, a command - make
(4)Command w/arg - make install
You can and probably should be regular user for everything but 'make install' - for that you need to su. And you can probably checkinstall (from /extra on your disks) and that'll make it easier to remove if anything goes wrong. Not that it will, of course.
(5)After installation, again no clue with what to modify, but the usage is clear enough.
./wlanup {ap|infra|adhoc}
./wlandown
Maybe a wlan guru can step up here and maybe some of this would help.
8180 stuff