In answer to your five questions above:
1. I, too, like to wear my watches and rotate through 6 different models, mainly the first three listed above. (I love the 5100G but the blue dial and small hands make it very difficult to read). So, the 5970P would get about 5 days a month and removed anytime during the day that it may be exposed to rough handling.
2. I simply reset the 5970P by carefully pushing the button at the 11:00 position to the previous day's date, then using the crown to advance to the exact time of today's date. Time, Day, Month, and date are then correct. Very simple and takes about a minute. Seriously! Never noticed if the moonphase is affected, probably not, but I don't really care about this feature if it takes another 5 minutes to set.
3. Definitely not, although setting the moonphase would be a pain and probably deter me from wearing it as often.
4. Wouldn't take a manual watch on vacation. Actually that is why I bought the 5960P, everything else stays home.
5. Sure, wear the 5070 upside down, but who really does that. Enjoying the movement is always a plus, but research shows that 70% of Patek's are chosen for the appearance of the dial. (this should get a response)
The advice given in the first response meshes well with the watches I own and the way I wear them. Some watches get a lot of wrist time, others less for whatever reasons. The main thing is to wear the watches you like and don't worry about little imperfections that can always be removed in the future, and you can always give new life to your watch with a new strap. I like my 5970P and 5070P best of all, but wear my 5960P (Grey Dial) most as it is ALMOST as nice, has an automatic movement and a chrono hand (full sweep) that can be left running without damaging the movement. Good luck, and be sure to try on both the 3970 and 5970 first. Size and dial may influence your decision.