Also I´d like to know how come that being a vasodilator and also blood thinner chili peppers are successfully used to stop bleeding? It has to regulate pressure to do that.

The reason chili peppers act as a blood thinner is because they are very high in natural aspirin (salicylates).  But they are also a fiber source and fibers act as a coagulant when in direct contact with the blood.  Other insoluble fiber sources can also be applied to open wounds to stop bleeding.

So the many friends I know who also attest to it´s efficiency in RAISING their low blood pressure must also be right.

But how can a vasodilator and blood thinner regulate low or high pressure and not just high pressure? Can it be because of some special sinergy?

Cayenne is good for dilating primarily superficial blood vessels, but to a much less extent deeper primary blood vessels.  This will still lower blood pressure though, just not very strongly.

Most of cayenne's blood pressure regulating effects actually stem from the support of the adrenals by cayenne.  The adrenal glands regulate blood pressure by the excretion or blockage of epinephrine release and by regulation of water balance in the body.

Also how come chilis are used succesfully for many stomach issues like gastritis and ulcers and even GERD, if it is an irritant?

Gastritis is inflammation of the stomach lining.  Again the adrenals control the body's inflammation through the production and release of corticosteroids.

As for GERD, GERD is caused from fermentation due to a lack of stomach acid.  Cayenne pepper increases stomach acidity.

I thank you for the answers.

Also, changing subjects completely, what sites do you usually use and recommend for researching scientific papers and articles from?

For medical journal abstracts Medline (PubMed) is your best bet:

http://www.ncbi.nlm.nih.gov/pubmed/

 What about sodium docusate?

That is a stool softener. It is not going to treat varicose veins, but it can help prevent them by reducing straining during bowel movements.

 Does inulin act as a prebiotic?

Yes, both FOS and inulin are prebiotic fibers.