1) MMN requires conduction block for this diagnosis to be made
2) similar to other blood products, approx 1 in a million for HIV and 1 in 400,000 for Hep C
3) I'm not sure what you mean by new, IV immune globulin is the mainstay of therapy
4) depends, but there may be some fluctuation in weakness over time and in response to treatment
5) Yes
6) EMG is a subjective test especially in terms of judging whether more motor units are firing than before, your own impression is probably more sensitive, although the EMG provides more objective evidence than your own symtpoms.
7) I don't know enough about your symptoms to provide you with more of a diagnosis - fluctuating weakness, which is what you seem to describe can be caused by a wide range of conditions such as myesthenia, metabolic myopathies, periodic paralysis, or other immune mediated neuropathies like CIDP.
Good luck