I am considering booking and paying for Premium economy sometime in the next two weeks for a trip Oct 2017. In searching premium economy, I have found there are some standard fares that arent too bad. Just wondering if it is best to book early for one of these fares.

Do they block out some seats in Premium Economy to sell at the higher fares?

The consensus seems to be the first row is not good because the foot rest is too far away. True?

Trip will be SFO to VCE.

Am I more likely to get an upgrade offer to C, if I pay for PE?

Any other advice is appreciated. I normally fly United but cant book PE through United web site. May concern is comfort, not getting miles.