I can't help you with how to slap, but I can imagine you'll find a plethora of lessons on the internet by searching on google.

For funk bass try this - always try to hit the root or the fifth on the first beat. Now, playing in a syncopated manner, use other notes in your bass line (the 5th, b7, and the octave are common staples for funk bass lines).

Another tip - leave a lot of space. The bass in funk is just another instrument in the groove, so it should really blend in and not become overwhelming.

"Chameleon" by Herbie Hancock is thought by some as the quintessential funk bass line. Pick up a copy!