So for the album thumbnail - I've set the thumbnail size under Options > Themes > Crop Thumbnails to crop to 230x300px. All looks fine when I do my custom cropping of the thumbnails in admin view.

It has some issues when displaying however. I'm using:

You probably should not be supplying both the height and width for the thumb size. Unless all your images are the same dimensions, that will not work. (And since you have some that are portrait and some that presumbaly are landscape, they will NOT be the same dimensions.)

Do you want your thumbnails to all be landscape? If so just set the height variable to NULL.

I'd prefer to give the option of landscape or portrait if possible. I just thought it was strange because it seems to crop to the correct size when cropping, just doesn't display that way!

Look into the max size functions then.

Will that display the custom crop? Where can I find more info on it?

The maxspace functions do not crop. They size images to a fixed width x height space you set. Info on function as always on our user guide.