Yes it blocks other opioids but not quite like methadone does. On bupe in the correct dose (too low of a dose and this doesn't happen) you just can't feel it no matter what you take. It takes much less bupe to have a blocking effect than an equivalent dose of methadone.

The dosage depends on what your doctor tells you you need But since no one cares about that, the dosage you should take is based on how what opioids you take, how much you take, and how long. If you can't or won't go to a doctor, you are really playing with fire and IMO set yourself up for relapse; but anyway, start low and take as you need, taking more every hour as you see you need it to relieve withdrawal. Unless you have a huge habit, use the 2 mg's. Both Suboxone and Subutex comes in 2 mg and 8 mg strengths.

Suboxone is buprenorphine and naloxone (to prevent you from injecting it), Subutex is straight up buprenorphine.

-yawkaw