Proactiv is a benzol peroxide based skin care line that is aimed at treating acne. It is endorsed by big name celebs, but at the end of the day the main active ingredient is benzol peroxide which is available in cheaper formulations on the high street. The side effects are probably the same as you are experiencing with your current topical - dryness, peeling, perhaps redness. Benzol peroxide and other topical treatments are usually only recommended for mild acne.
Tetracycline is an oral antibiotic. I think it is generally the first line of defence in the treatment of acne because it is one of the cheaper antibiotics, but others, such as minocycline, doxycycline, bactrim are used. Antibiotics work by killing off the bacteria in your system that contribute to the development of the lesions. Short term they can be very helpful. I don't know enough about tetracycline in particular to know about the medically recognised long term effects. Generally though, long term antibiotic use can reduce their effectives at killing bacteria over time. Also, holistic practitioners will tell you that long term antibiotic use depletes the beneficial bacteria in your digestive system which then gives rise to its own health problems. Antibiotics as an acne treatment tend to require long term use because when you stop taking them, the acne returns, unless you naturally grow out of it in the meantime.
Accutane (Roaccutane in the UK & I think Australia) is not an antibiotic, but I don't know what category of drugs it falls into. It is the only treatment that is medically recognised as potentially working permenantly, but even then a permenant cure is not guaranteed. Unfortunately it can come is a number of side effects, but most are mild (i.e. dry skin, hair, lips) and temporary. However some are more serious (foetal deformities in pregnant women, hair loss, irritable bowel syndrome etc etc). Roche, the producer of the drug, produce a pamphlet containing a very long list of side effects and if you do an internet search you will a number of scare stories. However, information available at the moment suggest that the more serious side effects are uncommon and temporary (and in respect of feotal deformities, completely avoidable by not getting pregnant during the length of the treatment). Because of the side effects, Accutane is usually reserved for very serious cases.
I have not heard of the other treatments mentioned here.