1. If I have a naval unit with movement allowance 4 and range 3, I could take it out of port and then place it in the 3 section of the sea box it just moved to. You need a movement allowance of at least 5 to be able to move directly into a 4 section - right? I could not weasel around this by reactivating a unit with movement allowance 4 and then spend zero range in order to move it "up" into the 4 section?
2. In section 13.4, return to base, it states that the movement allowance of a naval unit returning to port is reduced by the sea-box section it is currently occupying. However, no such reduction is mentioned in the rules concerning naval movement, 11.4.2. Does that mean that I can have the unit mentioned above (movement allowance 4, range 3) patrolling in the 3 section of a sea-box, and then move it through two sea sections and then into a port if I move it during the Naval movement step and not during return to base?
1. Yes a movement of 5 is required to get into the 4 box of the sea area next to the port. And no you can't "reactivate" because you can only move a naval unit at sea either down to a lower sea box or back to a port.
2. Nope. A "return to base" is a "return to base" no matter when you do it (and is identified in section 11.4.1 c as such) so the rules in section 13.4 apply. The movement allowance is reduced as noted in 13.4.