Being one of those "50something year olds" ;), I'll give you a few of my habits that I have developed over 35 years of travel.
I carry a back pocket wallet at home, but not when traveling. I use a neck wallet when moving from place to place on planes and trains. It's easier to pull it out of your shirt than to take out a money belt. As soon as possible after arrival I sort everything out and stash my passport and all but a day or two of cash and the cards I will be using short term in the hotel safe. An in the room safe is best but most hotel/hostales have one behind the desk. Go back when you need to. Ask for a receipt. On the advice of Spanish friends, I carry a scanned copy of my passport. In 30+ trips to Spain there has never been a problem. On the street I put my credit card in a buttoned front shirt pocket. For cash I fold up everything over 10 euros and put it fold end down in my watch pocket. It's almost like a lever, difficult to remove.
I keep a data sheet with all the bank numbers and websites and phone numbers and email it to myself. That way it is always secure and accessible from any internet cafe.
I keep a separate credit card for obtaining cash than the one I use for shopping, hotels and restaurants. It's easier to keep track of payments and interest rates. I always use credit cards for getting money. It may be a bit cheaper to use debit cards, but several times I have had errors with debit cards, and until the problem is reported, they have your money! If you are worried about the high interest, pay it off the day you get home. (Or even from Spain. The internet is a wonderful thing for travelers!)
Finally, shortly before departure I always send an e-mail to my credit card companies and bank telling them where and when I will be travelling, including my home and connecting airports. It has saved me much trouble.
Sorry, I can't help with the middle of the night bathroom thing!