Masquerades queries

[Masquerade]

I had noticed that the AI appeared reluctant to pursue once it had driven me off land.
I'd assumed this was because the units available to them via coastal provinces in the map were judged insufficient for the task by the AI and/or they had no amphibious summons/chose not to dedicate their gems to summoning them.
I'm assuming, from NT Jedi's comment, that this isn't quite the whole story and that regardless of their capabilities in assaulting me in the sea they'll choose not to. Is this so?
If so that's quite disconcerting, personally I'd rather get my bearings with the game on a bit more level footing with the opponent. Would there be any way to encourage the AI to be more confident or overcome whatever holds them back?

Just another quick question while I'm blabbing. I'm currently a bit uncertain about the transition from land to sea income and resource wise. The manual didn't seem too clear as to whether coastal forts gathered the excess resources from adjacent sea provinces or not - same for sea forts to land provinces so I'd appreciate if anyone can clear that one up for me. Umm, also I'm under the impression that land provinces produce more resources or income or just generally are better all round. Am I right in this and are sea based nations at a distinct disadvantage therefore?