What are the implications of "at my disposal"

Solution 1:

As a correction to your third paragraph, someone who is not available at some point in time is said to be indisposed. I am not sure where "already disposed" is used and deemed correct, if anywhere.

A thing, service, or person at your disposal may be under your control or available at your convenience. The degree varies with context. We sometimes say "at my complete disposal" or "at your utter disposal" to intensify the sense of control.

To dispose of a thing means to handle it as you see fit. Context is derived from the nature of the thing itself. With firewood, it means depleting the supply as you wish. With a task, e.g., "please dispose of this matter," it means to handle or complete it; how you do it is not important to the speaker. In action movies with bad dialog that is meant to sound dark, disposing of someone means to kill them as if they were a bothersome detail.

Solution 2:

My question arises from the word disposal. It seems to imply that the resource is gone once it is used. As in, "I disposed of the trash".

The verb "dispose" differs from the phrasal verb "dispose of".

dis·pose  (d-spz)
v. dis·posed, dis·pos·ing, dis·pos·es
v.tr.
  1. To place or set in a particular order; arrange.
  2. To put (business affairs, for example) into correct, definitive, or conclusive form.
  3. To put into a willing or receptive frame of mind; incline. See Synonyms at incline.

v.intr.
  To settle or decide a matter.

n. Obsolete
  1. Disposal.
  2. Disposition; demeanor.

Phrasal Verb:
dispose of
  1. To attend to; settle: disposed of the problem quickly.
  2. To transfer or part with, as by giving or selling.
  3. To get rid of; throw out.
  4. To kill or destroy: a despot who disposed of all his enemies, real or imagined.

from http://www.thefreedictionary.com/dispose

A professional soldier at the disposal of a general may prefer to be disposed than disposed of.