Last year my group just brought one of those chemical sprayers you can buy at home depot and used that to "shower" with. Works like a charm and it's only like $10 or $15. Just fill it up and pump it a few times and you've got yourself a pretty decent shower. Definitely better than the "leave a bottle in the sun" trick and isn't nearly as much hassle as setting up a legit camp shower.
As for flag poles, we've always just used a 12' section of pvc and attached it to one of the legs of our best / strongest canopy. Gives you a good 10' of height above the canopy, so it's easily visible. Just use LOTS of duct tape to make sure it can stand up to the winds, and please do the rest of us a favor and make sure your canopy is staked / weighted down so it doesn't go flying!