1 defenitly not!
But... maybe it's a feeling... maybe luck
My level 9 brings much more 5000 food on 2nd account then my level 10 on main account.
I get more 5000's when my foodstock is 1.000.000 or higher (as most of the time on 2nd account...)
3 no Against a common, a common has same changes as an ultra IF they have same gems and level. But it depends on much more then rarity...
4 no I had an account at 4 and another at 1, no differences over longer time...