Jabba Degrassi

I can't think of a better place to post some newbie questions. If this would be better directed somewhere else, please let me know.

A little background: I'm riding a 2008 Jamies Exile 29er SS, stock. I am a complete MTB newbie.

Now that we've got that out of the way. Little help?

I took my first real mountain ride this weekend, and it totally kicked my ass. My problems included:

1) Absolute terror. Taking tight turns on narrow tracks and seeing BIG drops to either side of me. I ended up walking a lot because I just wasn't sure I could navigate a particular section, and was pretty sure that if I failed to do so, I would go flying down a cliff. Even on fairly safe sections I got pretty scared. I remember one section in particular which took me downhill over a ton of roots, then across a narrow bridge, and a small climb afterwards. My friend eventually got me to do it, but it took a lot of cajoling, and even then I felt like I was barely in control.

2) Climbing. Maybe I'm just a weak little girl, but on a lot of uphills I would find myself pedaling as hard as I could, and at some point, I would just stop. I would lose all forward momentum, and tip over. Other times, I would start to wheelie involuntarily.

3) Twitchiness and bad lines. I don't know if it was just nerves, but I felt like my front wheel was all over the place. I felt really uncomfortable on narrow passes, and I'd be wobbling like crazy. At one point I took a pretty nasty spill, as I was headed downhill on a series of about three fairly tight turns, at the bottom there was a fairly wide bridge, but on either side of it was a DEEP concrete V-shaped gutter. I took the turn wide, my front wheel slammed into the gutter, and I went over the bars. Several other times I found myself drifting slightly off the track, and because the ground was angled, I would just tip over on my side and grind to a halt.

Any suggestions? Is this pretty normal for a first ride? It's just hard to think about stuff like "keep your feet at 3 and 9" or "lean back for x, lean forward for y" when you constantly feel like you're about to careen off a cliff to your death.

edit: Platforms or clipless? I've got a set of Crank Bros. MXRs which came stock on my Exile, but I've also got a pair of 50/50s I could use. I tried riding clipless on the ride in question, but, even though I ride clipless on the street without issue, I felt really uncomfortable on the trails. Should I switch to platforms until I get a feel for it?