I am replaying all the missions strictly linearly and I am not finished (so no vote yet). There were only 35 of them when I last installed the game, so a lot should have changed.
On the Monitor vs Virginia missions. The first one should be doable once you realize that you can enlarge your Monitor to carry two turrets. The second one depends on luck, but the following strategy helps. You will notice that at some point in the batte the Monitor will stop (this also happends in the first mission, in which the Virginia stops). You need to cross the T of the Monitor with your Virginia when this happens and stop your Virginia in the T position relative to the Monitor. With some luck, your should then be able to burn the Monitor with your HE broadside while the Monitor will be able to bear a single turret only (which hopefully gets disabled soon).
The next mission is Hurry Up. Any advice on what class to build?
EDIT (while waiting for moderator approval): Hurry Up is done, with a single fast battle cruiser!