Don't bother with a bar code. Have your cover designer leave space for it; they know to do that, anyway. Ingram and KDP will insert barcodes. There is no value in getting arty about barcode placement, either. Those barcodes, as far as I know, will have your print ISBN on them, but not your cover price coded in. This is good because you may want to change the price and doing so won't mess up what may already be printed (such as if you get a bunch of author copies to sell at a convention or book fair) or set up at the printer for POD (Print on Demand).
As I understand it, the templates/specs for Ingram and KDP do vary slightly. If you know formatting or have a good formatter who can make sure the specs are right for each company, that should simplify things.
If you can reasonably foresee selling a lot of print books and very few ebooks, you can do the print book first, but most of us upload the ebook and the print files at more or less the same time. It's not a big deal and it might take ten minutes per site, especially if you gather together your metadata in advance so you're not staring at BISAC codes and wondering what categories to choose or what keywords, or worrying about writing the blurb or rewriting it for each sales venue, or not sure of what price to charge.
Granted, if you happen to be publishing, say, a dozen books on the same day, it's going to take you a little longer to upload them than it does for just one title. Get organized in advance and it'll be easy. Keep a record of what you choose on each site in the way of prices, keywords, and categories. You may want to change all three elements at some point in the future. In fact, you're sure to want to.
Good luck. Ask more questions if something is unclear.
