Welcome to the forum. Thanks for your question.
I haven't looked at the link you provided, which is protected by your LabCorp username and password. But I can tell you that all HIV tests approved for use in the United States, and therefore all the tests offered by LabCorp, are highly reliable. There is no need for me to know exactly whiich test you had. To your specific questions:
1) Yes, your 8 week test is conclusive. In case you are confused about common advice to test at 3 months or more after the last exposure, please see this recent thread:
http://www.medhelp.org/posts/show/1704700
2,3) The HIV diagnostic tests are among the most accurate and reliable blood tests ever developed, for any infection. They are designed to be unaffected by other medical conditions or drugs. The only possible exceptions are terminal illnesses, like advanced cancer, or potent cancer chemotherapy or immunosuppressive drugs -- and even these are theoretical only, with few if any actual reported cases of inaccurate or delayed test results.
4) You can definitely "go on and put this behind [you] and not worry about HIV anymore".
My final advice is that I hope you will get in the habit of using condoms for future sexual contacts with commercial or other non-monogamous partners. Although the risk of HIV is low for any single exposure, even if your partner had HIV, you could avoided several weeks of anxiety. Also, since you didnt' use a condom, I hope you have tested for other common STDs. If not yet done, you should be tested now for gonorrhea, chlamydia, and syphilis.
I hope these comments have helped. Best wishes-- HHH, MD