#1
Hey I really love listening to these two genres, but really have no idea what kinda scales and chords are often used. What are some common keys used for each of these genres?

Bands such as Funkadelic, RHCP, Sly and The Family Stone, Sublime, Bob Marley etc

#2
pentatonic minor
regular major and minor scales
learn some simple voicings of the seventh chords (dominant, minor, also major, probably a couple of diminished/halfdiminished in there too) and the other extended chords (9th and 11th chords)
#4
Ska HUGS the Cmaj scale.
Most major scales in fact.
But you aren't limited by all means to major scales.
Really if you learn ska, you can pretty much pick up the basics to funk pretty easily. And visa-versa. Just when your playing real ska (1st, 2nd Wave) or funk with horns etc, you have to realize that the ska guitar isnt the main instrument pulling off sick riffs. In-fact ska guitar can get very boring. I'm not saying that you can incorporate a great lead and a cool chorus line (3rd Wave Ska) but, your really supposed to make way for the horns.