Pretty easy tho you most likely need to use a web browser. 

 So, to that, I would say to enter it when you write it, so that you and YNAB know that it has been “spent”. you could theoretically, with a regular bank register, move it to when it actually went out, but that might affect your YNAB budget history so I would advise against it

 it’s not really money to you until you cashed or deposited it, so I will probably just do the date that you did so

No, because you don’t have a online login for the backend bank.

I’ve had a mint.com account for years so I just use that. View the account, export the new transactions, and import into YNAB