Suggestion 1: not feasible at this stage. Selection is currently based on bounding sphere or box instead of real geometry.
Suggestion 2: feasible - I keep it in mind.
Suggestion 3: Similar to 1. Not sure that it is currently possible.

I had a feeling that it would probably be a bit tricky to get number one and three. 😃 Looking forward to number two, it could help a lot on larger models.

Ooh yes, I've actually been running into this recently. A follow up to Suggestion 2 ^ , It would be nice to be able to DE-select a group from selected parts, whether the group is "locked" or not. Currently if I select a number of parts and I wanted to not select an established group along with them, I have to carefully select or deselect individual parts.

Thank you so much!

I was going to suggest a selection addition as well; since some parts get selected when you don't want them to, there should be a way to click the unwanted selection and have it be deselected. There isn't a method or feature that I'm aware of that does this.

@Neckhorse, If you make an area selection using B key shortcut and then hold down Ctrl key you can deselect unwanted parts in your selection by clicking on them with the mouse. This doesn't work on groups though so you have to deselect part by part...