#1
I'm on an Epi LP, I use Ernie 11s and have some extra 10s. Any downside to switching between 10s and 11s every few weeks and besides intonation changes? Mainly talking about neck issues.
#2
if you use the same tuning all the time probably not to much of an issue. you may have to adjust the neck occasionally.
#3
I've often wondered this too, haven't had any problems but always wondered whether it would come back to bite me in the ass