Odd question; but is it possible to play as red humans or blue orcs through mods or otherwise?

Thanks

No. We wouldn't get that ability until Warcraft 3.

if you are playing mulitplayer and both pick same race orc, you will see your base as red color and your friend blue, your friend will see his base as red, and your color as blue

if you are playing mulitplayer and both pick same racehuman, you will see your base as blue color and your friend red, your friend will see his base as blue, and your color as red