Too many idioms!!

[Tdol]

1 How many idioms would you reckon would be a good for number for such a list?

We could in theory have an expanding list as well.

2 Other than feedback as mentioned earlier, any thoughts on selection?

[IHIVG]

I'm curious how many idioms do other natives recognize.

Perhaps, several people from different sides of the world (US, UK etc.) would suggest the ones they think are the most common. Then coordinate them with others' suggestions; the matched idioms would make the final list.
(I could also suggest some that I get to hear most; and trust me, I never memorize idioms unless I see them actually used somewhere).

[mmasny]

I agree with IHIVG. Fixing the number now seems pointless if we want to obtain a list of all (or almost all) really used idioms. I think making a list of for example 300 most used ones is, if not impossible, very hard to do by so few people, that would it for free.