Questions on landing at a towered airport

I should know the answers to these, but have gotten some conflicting
opinions without much authoritative reference, so wouldn't mind some more
from this NG .

When approaching a towered airport (Class D), suppose I am told a few miles
out "report a 3-mile right base, runway 23"... as often happens.

* Just to confirm what I think is true about what the controller wants me to
do: Fly as directly as possible (in the absence of other guidance, not
crossing the field or other downwind / upwind legs, and practicing
see/avoid ) to a point that is 3 miles away from the extended centerline,
and will intersect the extended centerline on a base leg to leave a
comfortable, but not longish final approach path, say a 1 mile final. E.g.
1 mile from the numbers on final, and 3 miles from the extended centerline
at a right angle, effectively a little over 3 miles straight line from the
numbers.

* Now when i am there, and report a 3-mile right base, if he tells me
"cleared to land, runway 23, you're #1", is that a hint or OK to dispense
with a squared off pattern, and make straight for the numbers, as reasonably
as I can manage in terms of flying the airplane safely?

* Do I really need to plan my descent so that I am TPA when reporting the
3-mile right base? I Really do not want to be. I'd rather be 2000 AGL,
which will give me a comfortable (but a little aggressive) descent with a
squarish pattern to the numbers, but also make much more feasible landing in
the airport environment, if not the numbers, should the engine stop. At
1000 AGL 3 miles out, there is just no hope of making the airport -- I'd
rather not be that low unless I really need to be. Is there any rule that
says I need to be at TPA when reporting to the controller points on the
pattern?

* Lastly, I've never flown into a Class C (or Class B) airport, but have a
fair amount of experience at Class D fields. Oh and I'm a new PPL with
circa 100 hrs. Is there anything I should be concerned about flying into a
Class C for the first time, or is my experience working at Class D and with
controllers going to serve me quite well? The two things I have heard is a)
don't expect to be reporting points on the pattern, you'll probably get
vectored to a final approach course (and that sounds easier), and b) brush
up on what you need to do for wake turbulence avoidance, since that will be
more probable....

Appreciate the thoughts and opinions of others with more experience!
T