I'm also in the "not too keen on crashing on descends" category. That whilst road-riding... (Yeah okay, stop laughing!) Started this mtb thing recently (in Dec) and was, needless to say, scared out of my wits the first couple of times - loose stuff moving under the tyres, sheeeet - madness! And just got more and more used to it, relaxed and went with the flow. First open gravel roads, loose gravel and rocks and rutting after our rain season, now venturing into single-track - where low and behold I'm crashing more than staying on - but at least it's not doing 50kph+!
Mentally - relax! And yes, you go where you look, so stare at the rock and you're staring at the crash zone. For me the biggest "technical" thing was to steer with your hips - just throw the bike into the turn as part of you. (Don't over-think the process.) And to trust the bike - it handles much more than you can imagine.
Was on a road bike for the first time in a while this weekend and we rode two mountain passes. I was usually first up, last down. Suddenly I was quickest down...
So in short - my message is to just go out there and do it, your confidence will grow and you'll do it quicker and more relaxed. Tackle obstacles progressively and build up your confidence. Right or wrong - that's the way I'm approaching the ST challenge now.