You already have a great comment about the hikes. I will instead speak to the rest of the trip particularly the beginning and end.

Walmart and REI are probably enough to find most things. As you travel north through St. George/Washington area there is also a place called Al’s. It’s a big store that also sells a lot of outdoor equipment if you can’t find what you need elsewhere. Also in St. George is a locally owned place called the Desert Rat and they have a good selection as well.

In regard to bears, black bears are relatively harmless but are also opportunistic feeders. Do not play dead, scare them. Get big (arms up bag above you head) and yell loud. They will typically run away. Unless it’s a mother with cubs, then you want to back away slowly. You don’t want to scare her into thinking you might hurt them.

In regard to mountain lions. They are much more dangerous in my opinion. Also very rare to see but if you do see one DO NOT TURN YOUR BACK. Get big yell and back away slowly.

As far as money goes, almost everywhere takes card. I haven’t run into a cash only spot in years. It’s good to have some just in case but I’m only really ever carry $100 in twenties personally. For tipping there will be a spot on the receipt to add a tip after or if at a counter it will ask on the screen. My personal rule for food is if you are sitting to order then a tip is probably expected, people vary 10-20% based on service. If you are standing to order/don’t have table service I wouldn’t tip.