Welcome, Pain-in-the-butt, what a perfect name for what you're going through. I've been there with the Crohn's, fistulas, abscesses, and setons and can't believe I put up with it for 7 years before having surgery.
To answer your questions...
How has your quality of life changed? It's amazing now to have my health back 100%. I don't have active Crohn's anymore and don't have to take medicine or see doctors. Life with an ostomy is good.
Has there been any discomfort with the bag? Sometimes my skin gets itchy under the wafer, but that only happens when it's time to change the wafer, which for me is only once a week. Once I have a new wafer on, it doesn't itch anymore. Otherwise, there's no discomfort at all.
How long does it take to get used to it there? The first couple of weeks is a learning curve, and then it becomes so natural that you'll forget it's there, except when it's time to empty, which is only after meals.
How quick does the bag fill? It depends on how much I eat. Mine always fills up at night while I'm sleeping, but isn't very active during the day.
Any leakage issues? I've been very fortunate that I've never had a leak in public. The only leak I've ever had was one time overnight, but that was my fault, because I tried to push one more day out of the wafer.
I'm glad you found us here and are asking questions. It sucks to have Crohn's, but thankfully, surgery will give you your life back. Good luck and keep us posted on how things are going.
Dx'd Crohn's in '99 at age 28. Proctocolectomy and permanent ileostomy in '06.
Disease-free and medicine-free since surgery and very thankful to be healthy again.