This is actually not one question, but a bunch.  Generally, the average
procedure can be done with one cartridge of anesthetic.  There are about
1.8 cc. of anesthetic solution in the cartridge, and anesthetic
solutions tend to be between 2% and 4% anesthetic by weight.  A quick
calculation (correct me if I'm wrong guyz) is about 36 mg of anesthetic
for a 2% anesthetic cartridge.
    Older anesthetic solutions such as procaine (Novocain) wore off very
quickly, and epinephrine was added to increase potency and duration of
anesthetic.  Still, procaine caused vasodilatation, so the epinephrine
was partly to counteract this effect.  Lidocaine also causes
vasodilatation (though not so much as procaine), but some anesthetics
such as mepivacaine and prilocaine cause little or no vasodilatation.
So these anesthetics are available without vasoconstrictors added.  They
are still not as potent as the anesthetics with vasoconstrictors, but
they generally are adequate--and are preferred either with patients with
cardiac history, hypertension, or where shorter duration of anesthesia
is desired.
    Just how much anesthetic is required is determined not only by the
potency of the anesthetic, but also the depth of anesthesia required.  A
root canal (for example) will require much greater depth of anesthesia
than a scaling.
    The duration of anesthesia is also influenced by the location and mode
of administration.  Generally upper teeth can be anesthetized by
depositing anesthetic in the gum next to the roots of the tooth.  This
generally does not work for lower back teeth (though some maintain it
does with certain newer anesthetics) and so the anesthetic is deposited
on the inside of the lower jaw where the nerve trunk enters the jawbone.
 This type of injection (nerve conduction block) generally gives
longer-lasting anesthesia than depositing next to the roots of the upper
teeth (infiltration anesthesia).

Hope this helps,
Steve

Good observation. Some anesthetics are more potent, others more long
lasting. Besides we dope some anesthetics with epinephrine at
1:100,000 or 1:200,000 or 1:50,000 for various procedures.

Marcaine has the longest duration ... many hours.

Joel