A few Q's that have been on my mind lately.

1) I've always been under the impression that a commercial certificate
is required to get the instructor certificate, but once you have it,
the commercial license is not needed anymore. This explains why you
can still get paid to instruct and sign students off without a valid
medical certificate.

So if you were to forfeit your commercial pilots license, of if the
FAA were to revoke it, you could still sign endorsements and do flight
reviews. Is this correct? If so, whats the point of the words "Must be
accompanied by pilot certificate #XXXXXXX" on the back of the
instructor certificate?

2) On sectional charts, the tops of class D and class C airspace is
listed as either [45] or [-45], meaning "up to and including 4,500ft",
and "up to but not including 4,500ft" respectively. I'm wondering,
whats the point of distinguishing between the tow? I assume one means
basically "from the ground to 4,500ft", while the other one means
"from the ground to 4,499ft". Whats the point?

3)Typically speaking, how do military airfields take to civilian
traffic landing there? There are a few Navy and Air Force airfields in
my area that I think would be pretty cool to do a touch and go at.
Theres this one thats about 50 or so miles south of me called Lemoore
which doesn't seem to be very busy at all. Heck, I think the tower
even closes on weekends.

They all say "transient traffic prohibited unless prior permission" in
thr AFD, but how strict do they hold to that? I guess it's different
from one place to the next, but generally speaking, if I were to call
them up, will they laugh at my face? Will they be like "oh yeah sure,
just call tower up before entering the class delta"? This goes for
private airstrips too.

I recently hit my goal of visiting every public use airport within a
100 mile radius of my home airport. Now I'll get started on the
private use ones. 8)