Recently took up bass as well. In general, it's not too difficult, depending on the genre. If you're doing emo, then it's pick and hammer. More challenging are the jaco pastorius, jamiroquai type songs. One featuring really fast finger picking, and the other some pretty interesting slapping. I found that the thing that was the most alien for me, was the rhythms. For slaps and pops, theres a certain bit of paradiddling to give some variation to triplets and sixteenth notes. That's when it really gets interesting.
A 6 string is an interesting place to start, but it's going to get really heavy very fast. Would recommend probably a 5 string instead. The top 5th string is a low B, so it's just like a guitar without the 1st and 2nd strings, and an extra low B.