Is it a decent generalization for simple cases to suggest that (when solvated) a primary amine is likelier to be deprotonated than a secondary amine, which is likelier than a tertiary amine (i.e. pKa is lowest for primary amines and highest for tertiary amines in general)? Conversely it would be the case that a tertiary amine is likeliest to be protonated (i.e. lowest pKb), followed by a secondary amine, followed by a primary amine. Of course, if there is any positive N, it will accept no more protons and will instead be likeliest of all to unload the proton it has.
I want to know about how imine acidity/basicity would work. Does the C=N make the nitrogen more basic (if it is tertiary), or more acidic (if it is secondary)? Compared to the amine?