Idioms

I own a dictionnary of "idioms", and really most of them... I never heard!! So I want to ask if you ever heard... Or more important: do you ever say:

"to over-egg the pudding"
"to be in the pink"
"to be much of a muchness"
"to be like gold dust"

I've got a lot of them, if you want to tell me...

I've never ever said them, but I must say that I'm not even sure of what they mean. I think the first one means to do too much. And the fourth one, maybe something like being rare...

"to over-egg the pudding" = to do too much (indeed)
"to be in the pink" = to be great, really fine
"to be much of a muchness" = to be almost the same
"to be like gold dust" = to be rare (well done on that one too )

"To be a cut above"?