i'd say you do worse mostly because premium ships have a higher weight in match making i feel. e.g. enemy team gets 1 atlanta, other team gets 2 T7's vs the team with the atlanta.
No, not with premium ships but with premium time active. There are a lot of tin foil hat threads associated with it.
Also, just because I feel like everyone should feel my pain, here are my ranked results this evening:
Rank 3.25. For fuck's sake I just want this to be over already.