The above quote covers the ADR question. If you are going to be eating during that time, just don't take one for that time. Wait a few minutes and the time will probably line up right for you. There is an allowable 15 minute grace period being followed but there are a lot of maybe's connected with it. If they are not too busy or are unable to accommodate for some other reason, they will say no and have been pretty consistent on not going over the 15 minutes. It would be a big risk considering factors such as, how quick the ADR service is. Really not worth the risk.
The second scenario happened to me on my last trip. After getting my Fastpass, I found that the time conflicted with another activity that members of my party had set up (while I was getting the Fastpasses). I simply went back to the kiosk, which by then was windowing at a time that would fit, found a group with the current workable window time collecting the same number of Fastpasses and I approached them and asked if they wanted to swap theirs for an earlier time. First people I asked, gladly swapped with me and we were all happy. It took about 5 minutes out of my time and saved probably an hour of standby time.