If your employer closes your 401k account (usually because of dollar amount in account), you must still rollover to a new 401k or IRS within 60 days to avoid the early withdrawal penalty.
I don't believe so. What is the code in box 7?
Generally, if you are bumped out of the plan after termination, you have 60 days to rollover the funds into a private IRA or a new workplace plan. If you don't rollover the funds, they are taxable to you plus a 10% penalty if you are under age 55.
As far as I know, "Employer maintained distribution" means something else, like when a plan has to return funds because they failed one of the tests for maintaining an eligible plan (the plan must follow certain rules that you never need to know about, and sometimes those rules affect the amount each employee is allowed to contribute). That does not sound like the case here.