Also note that while Germany's production of 12 already assumes the blockade is in place, if Germany is able to lift the blockade and control the blockade box then Germany gains 1 PP each turn (for lifting the blockade) and Britain loses 1 PP per turn (due to easy access for commerce raiding). (Section 8.2.2). Of course, this goes away if Britain is able to re-establish the blockade.
As Herm mentioned, Event Cards later in the game might impose further production penalties on Germany if the blockade is in place at the time the event is triggered.
I never tried it solo, but I can't see a reason not too. The cards are drawn randomly and you can just follow what they say. As for the overall strategy, I assume you could start off with a general Central Powers plan and just go from there.