Good post.

I think 10x is way too small if you are not winning some small pots when you miss. 15x I think is not hugely +EV. 20x is even better. Note that the more you are willing to play when you miss, the smaller effective stack you can call with pre-flop.

The reason is, most raises are NOT QQ+, they are 2 high cards. This is also why you open-raise with small pockets IN POSITION. You take small pots when you (both) miss.

As always, it really depends on your opponents. The weak-tighter they are the more you want to raise them, they will fold post flop (similarly, won't pay off when you set).

Also limping in EP with low pairs can be bad with aggressive short stacks behind you - they raise - but now you don't have odds to call, and just wasted a BB.