Its it required to name reservations?

No it isn't but is suggested went I was there last.

Yes

Unsure

Yes, absolutely required. On a weekend you'll be directed away from the entrance. On a slow weekday the attendant will do it for u, but not suggested. Reservations are an extra $2

Not technically required but saves time when you get there. Shorter line for those with reservations.

Reservations are definitely required. You can make them at "rec.gov"