I'll try to answer your questions:
1) If i think i might have Lyme, does it make sense to take ProBiotics (or some other vitamins/supplements) to help fight the infection until i start antibiotics? Vitamins and healthy eating are always a good idea. I'm not sure about the probiotics before starting treatment. They can't hurt though. There are supplements you can take (ie: Cats Claw) but I never had tremendous luck with them so I'm no expert. Maybe someone else will chime in with recommendations.
2) if i have a prescription for 3 weeks of Amoxiccilan 500 mg x 3 day, is there any benefit in taking it, or if i'm not gonna cont. more than 3 weeks better not to? This is a question for your doctor. I don't know if taking a three week course would be a good thing or a bad thing.
3) anybody here cured? how long were you on med. for? any lasting side effects? There are folks who have recovered from Lyme. They're out living and enjoying their lives again, so they don't post often. They do post so keep your eyes peeled. The length of treatment depends on many factors, for example, how long ago you were bitten and infected, how severe your symptoms are, how strong your individual immune system is, etc. I was infected for 2 or 3 years before my symptoms drove me a doctor and I have been taking massive doses of antibiotics for 3 years. I don't know how much longer it will take me to kill the rest of these darned buggers. Personally, I have no side affects, but that's just me.
4) when you're taking so much antibiotics for so long, are there side effects? (weight gain, liver damage, ) Like I said above, I have no side affects that I know of and my LLMD (Lyme Literate Medical Doctor) runs blood work twice a month so we'll catch any impact to my liver. I have major weight gain, but it was prior to starting treatment so it is a symptom of the Lyme, not the treatment.
5) About ProBiotics; if you can make some powder that creates 'good' bacteria, that means you know the difference bet. the 'good' and the 'bad'. if that is case, why do they make the antibiotics to kill ALL the bacteria, if they know the difference then let them incorporate that knowledge into the making of the meds.? If I could answer this question, I'd be a millionaire writing this from a south pacific island.
Fighting Lyme is a tough and sometimes very long road.
The best thing I did was to get myself under the care of an LLMD for Lyme and it's co-infections.
Are you seeing an LLMD? When were you bitten? What are your current symptoms? Are you under any treatment at all now?
Peace and health to you,