As for brain damage - all pain medications, and most substances in general, cause brain damage. In fact, living causes brain deterioration. I've read many, many studies. The side effects of marijuana on most of the body are negligible. The studies that get news time, outside of maybe certain shows in certain states, are all biased, poorly done, or at the least rephrased in a way to present the evidence incorrectly or in a frightening way. It's scare tactics, based in a complicated history about marijuana in particular as well as many other drugs that were at one time perfectly acceptable for medical use.
However, there are side effects, like any other medication. I don't really experience any, which is why I enjoy it so much. Some people get anxious, heart palpitations, temporary memory difficulties, hallucinations, seizures, and more. It actually helps me with my anxiety and seizures!
Smoking hurts your lungs but I much prefer the immediate relief of smoking. Then there's vaporizing, which is much less harmful than smoking, and also immediate. There's edibles, and pills, which are less immediate, last a long time, and are typically 'heavier'. I also like smoking because I smoke other herbs for pain and anxiety relief, plus I'm a tobacco smoker (I know, I know!
), so I smoke it all together. And it is my favourite medication. I only recently got my official diagnosis and I haven't started any pharm meds yet. Without weed I couldn't walk, go outside, eat! It helps my pain massively, my nausea, my insomnia. It really is a cure-all for me.
As for strains I'm pretty broke so I end up getting the cheapest. There are so many anyway, I would have a hard time narrowing it down! I try to get a heavy indica for sleep and body pain, and sativa for fighting fatigue during the day.