You can file a 1065 return as a single member, yes.
-1000
a Married couple can file either, a single person can't file a 1065
as a single member, the only thing you can do is elect to be an S Corp and file a 1120s
Supposedly yes. I personally know accountant’s who all the time recommend doing a 99.9/1 partnership to avoid using a schedule c
99/1 usually
the .1 or .01 not recommended