If you must...
1: Get what you can naturally. General rule of thumb is that if you are working resting and eating properly, you should be able to get about 20 pounds in the first year, 10 the second and 5 the third with a few pounds per year afterwords naturally. Give or take YMMV of course.
1A: If you are getting nowhere near this, you should learn how to work out to get the most out of the roids before you start.
1B: It is after the gains slow down that adding the roids really is beneficial. Why bother juicing if you are making beginners gains.
2: If I were after the above to the roids, again the same principle. The first cycle will get you the most, as I understand it the law of diminishing returns applies here also. Unless you are competing, there is no need to keep going at it. One or a few cycles, after a few years of training naturally and you will have much of the gains that your typical juicer would have. [Yes you will lose some of your gains if you quit, but not all, and yes you will be very small compared to those people who take horse sized dosages of roids, plus HGH and FSM knows what else.
3: As I understand it, there are some countries where it is legal. I'd be inclined if I were to do this to take an 8 week vacation to Mexico or whereever it is currently legal and do it safe.
The above is from reading, not from personal experience. Reader beware.