Can you get in to see your stoma nurse about
the infection? They would be the best ones to see - they can have a look at it first hand and recommend products for you to use.
As for products, no one system suits all. I would suggest contacting the various manufacturers, ie Coloplast, Hollister, Convatec, Dansac, etc and get as many free samples to try from them as you can. They all have websites and you can order the samples over the net. Just because one product works for one person, doesn't mean it will work for you unfortunately.
I would suggest sticking to a two piece non-drainable disposable system. The reason being that if you have a one piece system and are changing 2 - 3 times a day, your skin probably won't like it very much if you're attaching and removing a flange so often. If your output is loose, you could try a drainable system so you won't have to change so often - just drain the contents into the loo 2 - 3 times a day instead.
I have an ileostomy and so use a drainable bag. I use a one piece midi sized bag and so can't change bag size at wil. However, I don't have a problem swimming with a bag that size. I just wear mine angled towards the middle of my tummy and it all fits neatly into my underwear or swimming costume. I choose a costume with a pattern or splash of colour across the stoma site which disguises any slight bulges which might be there and at no time in 30 years has anyone ever commented they can see my bag.
A colonoscopy for colostomates can be either via the rectum or the stoma since both are part of the colon. Depending on where they are going to scope will depend on whether you need the prep or not. If it's via the rectum, then obviously the prep isn't going to reach there anyway so you won't need it. If it's via the stoma then you will need the prep because that is where your stool hangs out :)
I can't help you with the reversal bit but I'm sure others will come along who have had experience in that area.
I have had an ileostomy for 30 years now due to UC.
I'm not a complete idiot - some parts of me are missing!