Loosen your shoelaces. Those ankles will swell regardless. Call every airline you're flying to get their baggage limits - number and weight. On complicated itineraries, you can sometimes run into bottlenecks with commuter airlines that allow only a couple of bags. Pack an empty suitcase if you plan to do a lot of shopping.
Airlines are getting ruthless about carry-ons, so check size limits.
It duplicates coverage under your own auto insurance and the temporary policy you get when renting with some credit cards. Make the call. Phone your insurer to see if coverage is good where you're going. Also, call your credit card companies to find which one has the best rental benefits and what the exclusions are. Some don't cover certain countries or types of vehicles.