Originally Posted by Syscrush

First, if you do try to fix your bike, you will probably screw stuff up at first, but over time you'll learn what you're doing, and have skills that will last you a lifetime. So don't be too shy about getting your hands dirty! There are lots of helpful how-to's on YouTube, Sheldon Brown, here, and elsewhere on the web. Ask questions & do research, use the right tools, and give it a shot!

Secondly, Rattlesnake is a really tough climb. If you think that standing up when you're only halfway up (and not at the really steep part yet) is going to help make your legs less tired, you've got a whole lot to learn about cycling technique. I don't mean that as any kind of insult, but when your legs are burning out, you should be dropping down gears and keeping your RPMs up. I suggest that you should be doing some reading and/or some club rides to learn proper technique.

Lastly, if you're on the rightmost chainring, you shouldn't be on the leftmost 2-3 cogs, and vice-versa. The chainrings and cogs are arranged the way that they are so that you don't have to cross up the chain like that. It's not surprising if you have noise/skipping problems when running the chain crossed up.

Good luck getting this sorted out, and I hope you enjoy your long ride.