I ain't no guru but I do have a couple of ideas. I'd suggest epoxy coating your garage floor. You can paint it but it seems concrete paint never holds up over time as well as epoxy. You can use the kits at Home Depot or Lowes to do your garage. I used Rustoleum's kit and sealed my garage floor for under $150.
If you garage floor is flat enough you can apply vinyl tile in the checkrboard pattern, just like you'd do a bathroom or kitchen. I don't know what that would cost or about its durability but its an easy job to do.
Lighting is real easy with the light kits from HD or Lowes. They're about $20 or so for a 4 foot light so for under $50 you've got your garage lit up real well. Hang them from some s-hooks and plug them into an existing light socket in the ceiling if it has one. There are adapters that convert a light socket into AC plugs so all you do is plug in the light kits into it and use the on/off switch on the wall.
As far as separating garages, well.... ya better clue in moms and pops before starting major construction. What I'd suggest is some sort of curtain (think of a big shower curtain) to separate the two spaces.
Hope these ideas help.
