One other thing I meant to address in my previous digitally-diarrhetic post was the oft-mentioned misconception that to play jazz one needs to "lay back" or play behind the beat, and to stress 2 and 4. Those misconceptions probably stem from things we need to say as educators to young students who continuallly get excited and rush in order to get them to stop doing that. Yes, to be good at anything, you have to be in a mentally and physically "relaxed" state, but intentionally playing behind the beat will get you fired. A horn player, soloist, or horn section can get away with it, and even sound good doing so, for a few beats, but playing behind the beat as a non-soloing bassist is an unforgiveable sin. There's a comedic aphorism among sax players that "it is better to be sharp than out of tune," meaning that playing flat is far worse than being sharp. Same thing could be said in jazz, really, about tempo. Yes, rushing and dragging are both undesirable, but dragging is way worse. There's lots of famously recorded examples of great players ending up more than a few clicks faster at the end of a cut. Don't recall many where they ended up slower, except maybe a few ballads at crawling tempi.
As far as "stressing 2 and 4," at least in terms of a walking bass line and ride cymbal, no. Just, no. I'll refer you to Peter Erskine on that one. All four quarter notes should be as even as possible, and THE driving force behind all other decisions and playing. Wynton is fond of telling folks in clinics that not only should the ride cymbal and bass make sure the quarter notes are even, but that the combined VOLUME between the ride and bass should be 50/50, with each instrument being equally present. The stress on 2 an 4 comes from the high hat and from implied melodic inflection. The reason for telling folks to "stress 2 and 4" in the early years stems from a desire to impel the music forward, rather than landing on 1 all of the time which tends to "stop" forward motion.