Leave the ABS on. If nothing else, it'll save you from flat-spotting your tires (not common on street tires, but can still happen). Typically autocross courses are so technical, it's hard to avoid small lockups here and there with no ABS. If you have it, you can actually use it to fudge the line between braking and turning just a little.
I can say with no ego that I'm an above average autocrosser, and I've tried it with/without ABS on my NSX...and Interestingly, I've also tried it with both the old style ABS system and the new style (01+) on the same car. Even the old style ABS allows you to get a little "chirp" before it takes over, so if you're threshold braking the ABS, you're pretty close to threshold braking to lock. The newer system is more consistent about that, and less invasive when it does kick in. Either way, usually, when it kicks in while I'm autocrossing, it's helping rather than hurting my time.
TCS: Definitely off for autocross. I can attribute several spins over the years to my forgetting to turn the stupid thing off, trying to rotate the car on-throttle and the fuel cut putting me in a tank slapper.
For the street....turning the TCS off somewhere other than a closed course is akin to saying "hold my beer and watch this". If you're inclined to, stop and think, "is what I'm about to do really advisable, and do I really want to put the car in a slide...and if I do, have I had extensive practice getting it out of a slide?".
If you're driving reasonably, even in a spirited manner, within your skill level at say 7-8/10ths or so (which is my typical "dragon run" pace), it should really never come into play anyway.
'just sayin.