Is there a way to accept members/limit their powers

[Bvbblyjake]

First question - is there a way to put out a trello link, but an admin needs to "admit" or "accept" them to the board before they are on it

Second Question - Is there a way to make freshly joined people not be able to edit??

[Michael Pryor]

No but you could set up a google form and then after people ask to get access you could invite them to the board. 

When you invite people you could also set them as Observers. 

https://help.trello.com/article/732-adding-observers-to-boards