i just use a pick and play it like a monster sized guitar, kinda. other than that, i do standard fingerstyle and slapping. i'm not fast without the pick though :P
i started out on bass actually, mostly doing standard finger-style and slapping. then my bass teacher noticed i was better when i used a pick, and told me to ignore what the "standard" methods were, and just go with what made sense to me. i kinda like the picked bass sound better for stuff that demands clarity and precision. the brighter sound just makes more sense to me.
anyways, look up some videos of death metal bass players. i remember some good ones being posted here earlier...
death metal bassists that play fingerstyle often have their action extra low and use thinner strings, so they can play lighter and still have every note sound "hard". the lower action also lets the strings slap about a little more, and get a clunky attack that rings through very well. for triplets and stuff, i've seen players sneak in an extra finger, using three fingers. i tried it, and it's not too hard to learn.
if you plan on using your thumb for slapping or "thumb picking", then you should start getting that baby ready. when i knew i was getting a bass for my confirmation, i warmed up for months, just playing "thumb slap drums" on stuff. i was a huge korn fan, so i sat around listening to their music while slapping the table/desk with my thumb as if it was a bass string. i had the rhythm and durability down by the time i actually got the bass
so get those strings a bit lower, and maybe switch to thinner strings if you aren't going to tune it down. you should be able to get the notes loud as if you were playing it hard, when you're actually playing softer. this lets you go faster without wearing your arms out.
i could keep on stating the obvious, but i'll let you go on with it