Does the above acid taken orally and used in chelation therapy 
meaningfully clean out blood vessels and increase circulation?  If
so,what amount must be used, in what manner, and must a prescription
be obtained for its use?  Is this acid safe to take orally?

Hello pete99-ga,
After searching the web over it appears that no properly conducted
clinical trial has shown chelation therapy or the oral ingestion of
EDTA to clean out blood vessels and improve blood circulation. EDTA
can if given too rapidly in chelation therapy result in kidney damage.
Some people have died due to kidney failure. The FDA does not
currently approve chelation therapy nor will insurance companies or
Medicare reimburse for this therapy. The only approved use of
chelation therapy is to treat patients with high amounts of calcium or
heavy metals in their blood. Here is some information you might find
helpful.

http://www.quackwatch.com/01QuackeryRelatedTopics/chelationfraud.html
http://www.quackwatch.com/01QuackeryRelatedTopics/chelationpharm.html

EDTA is placed in a number of foods to prevent them from turning
brown. It is added in small amounts (100-300 parts per million). In
higher levels it does not appear to be toxic. However, it may interact
with other medications a person is taking and before taking EDTA
orally I would ask a physician.

http://www.wholefoods.com/healthinfo/edta.html

I also encourage you to talk with your physician about this treatment.
Not the doctor that is suggesting you do this. This treatment is very
controversial. The recent clinical studies do not show this treatment
to be helpful.

Take care,
Nealc-ga

Like most everything in science, the answer depends on the study.  
EDTA chelates (binds) divalent cations (calcium, lead, zinc, cadmium,
etc).
Theoretically coagulation cascade components (blood clotting factors)
will be inhibited by the removal of calcium.

Here are some relevant citations from Medline:  Enter the Medline
identifier (PMID) in the search box.  If you would like a reprint of
the paper write or email the corresponding author or perhaps a local
library will have a copy.

Knudtson ML, Wyse DG, Galbraith PD, Brant R, Hildebrand K, Paterson D,
Richardson D, Burkart C, Burgess E. 
Chelation therapy for ischemic heart disease: a randomized controlled
trial.
JAMA. 2002 Jan 23-30;287(4):481-6.
PMID: 11798370 [PubMed - indexed for MEDLINE]

Ernst E. 
Chelation therapy for coronary heart disease: An overview of all
clinical
investigations.
Am Heart J. 2000 Jul;140(1):139-41. Review.
PMID: 10874275 [PubMed - indexed for MEDLINE]

Christensen K, Theilade D. 
Edta chelation therapy: an ethical problem.
Med Hypotheses. 1999 Jul;53(1):69-70.
PMID: 10499828 [PubMed - indexed for MEDLINE]

Lin JL, Ho HH, Yu CC. 
Chelation therapy for patients with elevated body lead burden and
progressive
renal insufficiency. A randomized, controlled trial.
Ann Intern Med. 1999 Jan 5;130(1):7-13.
PMID: 9890856 [PubMed - indexed for MEDLINE]

Green DJ, O'Driscoll JG, Maiorana A, Scrimgeour NB, Weerasooriya R,
Taylor
RR. 
Effects of chelation with EDTA and vitamin B therapy on nitric
oxide-related
endothelial vasodilator function.
Clin Exp Pharmacol Physiol. 1999 Nov;26(11):853-6.
PMID: 10561804 [PubMed - indexed for MEDLINE]

Chappell LT. 
EDTA chelation therapy should be more commonly used in the treatment
of vascular
disease.
Altern Ther Health Med. 1995 May;1(2):53-7.
PMID: 9359786 [PubMed - indexed for MEDLINE]

Chappell LT, Janson M. 
EDTA chelation therapy in the treatment of vascular disease.
J Cardiovasc Nurs. 1996 Apr;10(3):78-86. Review.
PMID: 8820322 [PubMed - indexed for MEDLINE]

van Rij AM, Solomon C, Packer SG, Hopkins WG. 
Chelation therapy for intermittent claudication. A double-blind,
randomized,
controlled trial.
Circulation. 1994 Sep;90(3):1194-9.
PMID: 8087928 [PubMed - indexed for MEDLINE]

Grier MT, Meyers DG. 
So much writing, so little science: a review of 37 years of literature
on
edetate sodium chelation therapy.
Ann Pharmacother. 1993 Dec;27(12):1504-9. Review.
PMID: 8305786 [PubMed - indexed for MEDLINE]



A Google search on "orally administered" EDTA "chelation therapy"
found

http://www.gordonresearch.com/chelation_therapy_in%20lead%20nephropathy.htm
(on lead poisoning)
http://www.ftc.gov/opa/1998/9812/acam.htm
(FTC suit against ACAM about Chelation therapy claims)

I suggest reading the relevant articles, if still interested let your
physician read them and proceed from there.