mvgossman wrote:
They
told me to maintain 3000 "and you'll be OK". By this I assume
they meant "no traffic in the class D area at that altitude" but I
was unsure.

Nope, it means that they have an agreement with the tower to route
traffic through that area.

1. Can Approach grant clearance to go thru intervening class D when
VFR? I am accustomed to this as a matter of routine when IFR but I do
not know about VFR.

Certainly. As a matter of fact, the rules specifically say it is
their responsibility to handle it. Of course, reminding them that
you're heading for another airspace never hurts as you did. Sometimes
it yields a "contact FOOBAR tower on 118.5" or whatever).

2. Why was I given in effect "permission", but no clearance, to enter
class Bravo at 3000, therefore permission to bust class Bravo and
potentially get cited? Is it conceivable that a controller would be so
sadistic as to send a place through Bravo without clearance and then
bust them?

He was technically wrong, but you can claim you were at 2999 as well.
I've always found the difference between 3000 and +3000 (which they
do use in places) to be somewhat spurious.