Do I need to leave space over top plate at eaves when adding insulation if I have a ridge vent
They make thin foam inserts for the eaves to keep the insulation from filling the eave.
An example like these.
Yes & specifically for ridge vents whether or not you have eave or soffit vents. The reason is because the roof deck itself is what gets the hottest & will escape fastest. This is natural convection & your house will hate you if you get rid of it.
Conversely, in low temperatures you want house heat removed from contacting the roof deck to avoid condensation as well as ice dams on the exterior...if you're in a climate where this would apply.