I'm now quite disappointed with the lack of large brests But I might be able to help. Are you sure you havn't overfilled your dash pots? That can cause your car to be smokey.
In answer to question 2, no you don't have to take your carbies off.
and to
question 3, the needles in the carbies atm (if they are 240z carbs) should be fine to use. I've got stock needles running in my 260z and its a modified engine.