Oh i can chime in, as i have some experience with that:
1. There are a lot of places one can get testosterone without prescription in Canada (illegal, of course). I hope everyone here knows that testosterone is a steroid.
2. Testosterone itself is a powder, so you can find it in liquid, tablet/pill, and gel forms. The best way to take testosterone is to inject it (so liquid) as testosterone is not bioavailable.
3. While testosterone might improve erection it's not the only hormone that affects it. In fact, if i am not mistaken, scientists still don't fully understand the entire biochemical mechanism behind erection (apart from dick gets full of blood, of course). For example, the right amount of estrogen (female hormone) also required for erection.
4. From my experience, before going on testosterone, it's better to get your cardio and overall health in check.
5. If you have low testosterone, you should get on TRT (testosterone replacement therapy), as your quality of life will improve tremendously. Replacement doses are safe (talk to your doctor, though) and well studied.
6. No, you won't get buff on TRT even though you're technically taking steroids.