I have had my bag for a long, long time. I also had all of these same questions that you are having. It is ok to ask anything. You may not get the same answers or any definite answers at all. Everyone's body is so different.
For me, NOW, I know that I really should eat an early supper so that I don't have to get up several times in the middle of the night to empty. My food usually processes fairly quick. But it depends on what I am eating. So, if I am going to bed, say around 11 p.m., I like to finish eating supper around 7p.m. That way, I know that I won't be up too much in the middle of the night. But I like to snack thru the evening. So, I up some nights more than others.
As far as the air in the bag, I have pretty much figured out what causes most of my excess air. Remember, I have had mine a long time - lots of trial and error. You've heard the usual - gum, drinking thru straws, carbonated drinks, OJ, talking a lot, etc. Sometimes I get surprises tho!
I wear a 12" length Convatec 2 piece appliance. I fold it 2 times and it lays against my lower abdomen. And I wear snug undies so if/when I have activity, it just distributes across the right quadrant of my abdomen. A girl that I met shortly after surgery recommended I wear it that way. I tried it and have always worn it that way. Then at night, if I need the space for air, stool - it will unfold and fill as needed. I haven't had one pop in the middle of the night, but I am a light sleeper most of the time.
Well, I can wear my tight jeans, but I am not real comfortable in them. I really like the jeans that have a stretchy material in them. They look like denim, feel like denim, but they give a bit when you need it. I'm a believer. I tend to wear pleated dress pants - again they are more comfortable for me. And I choose not to show my belly. I am really kinda short waisted, and my previous surgeries pretty much extend from bone to bone - pretty long scars. Tho they have nearly faded away now.
I am so much more healthy now. I can travel, go shopping, go out to dinner at nearly any restaurant I want, go to Nascar races, work in the yard, go swimming if I want, ride motorcyle with my husband. I work part time in a large office pretty much on a daily basis, 7:30 - 12:30 or so each day. We are building a house right now, and I have been doing a lot of physical labor there.
Hayley, take Amey's advice - have a good cry. Get it out of your system and then wrap your mind around the positives. You are alive and you will be healthy again. You will be active and have a good, long life - god willing. I felt really depressed for a while after mine. And you know what - you are human. It's ok. Being a new Ostomate is a HUGE adjustment. That's no lie, but you will be just fine. Don't push yourself and expect too much from yourself OR your stoma.
We are all here for you. Even veterans need assistance or have questions now and then. I learn something new all the time.