Congrats on making a tough decision.
If I had any advice for you right now it would be to talk with your Dr and make sure you see a WOCN (Wound Ostomy Continence Nurse) well before surgery so issues can be raised and resolved.
I think it was crucial for me is that I made my WOC nurse come back out to mark a better location before my surgery. She first picked a spot that would be under my belt line and that my hiking pack harness would have covered. In some ways this first site was the "right" on in the way my belly "rolled" so to speak, but it was wrong for my lifestyle.
My surgeon told me there would not be enough margin to do anything but have a permanent colostomy, so I didn't have to ever wonder about it. Maybe that made it easier for me, I don't know.
I'll second what others have said, if you are tied to the bathroom now, that will all but go away. Yes, you will have to adjust and learn how to manage it, but I am very active, eat very well (too well!) and don't give a hoot where bathrooms are anymore. I can run, bike and will be swimming next week with my Boy Scout troop
I'm sure if I'm off on any of this someone else will pipe in. I know that I've been very happy with my ostomy, though it did take a while before I stopped treating it like it was made of soap bubbles that might break if you didn't treat it exactly right!
I'm much more laid back and realistic about the whole thing now.
And of course I have to say you should check out
http://ostomy.org/. Lots of support there.