I have not seen stuff on water wells yet for this quake. But, I vaguely recall that there have been water well changes after large quakes at great distances...maybe in 48 states somewhere for 64 Alaska quake...or 85 Mexico quake?. As far as before the quake in Missouri....I'd doubt that this was significant....I'd want to see changes in in various wells in different areas, and see the levels plotted over the year...to judge visually if it was significant.

As for question 2....Don was supplying lists of quakes the other day around the time of the Alaska 1964 quake, and there did not seem to be any unusual increase in large quakes. And, so far on the NEIC global list and on the California map, it seems quiet...no increase in global seismicity IMHO...even though I suggested soon after the quake that I'd expect an increase...guess I was wrong.

But, it has become well-established that P and S waves from M7.5 quakes can trigger distant (100s to 1000 km) small quakes (e.g., Landers), and static stress changes from such quakes can trigger or suppress other quakes within maybe 100 or 200 km. So, this should happen this time......but I have not heard that it is happening. Maybe this will come out later.

My wife saw that there was a seiche in lakes at Mammoth Lakes area, California....and an eruption of a mud volcano in the area of the earthquake..but these are different effects than you are talking about.
Chris