I didn't have to change shoes after my arthroscopy for a meniscus tear, so unless your existing shoes contributed to the tears I'd aim to stick with them, as its one less change to deal with during your return to running.
You'll be out for a little while after the op whilst your knee recovers, so its going to be around six months that you haven't been running. This is going to have had a big impact on your running fitness, so you need to start back slowly and accept its going to take you a while to get back to full fitness. Therefore you need to accept that you won't be able to run as fast as before for several months.
have a look at the mcmillan pace calculator, as it will give you predicted times for other distances based on your HM result (mcmillanrunning.com). Its not 100% accurate as we are all different, but should give you a good indication of what you could do in a 10k race.
I'd go with Millsy's plan as you need the intervals to push yourself harder than HM pace, and also the tempo to get used to running at HM pace.
One thing that may be worth considering is that my best HM times have been when I was marathon training - I ran sub 90 whilst preparing for my first marathon, and haven't beaten that time since (only getting close whilst marathon training last year). Maybe finding a 3:15 marathon training plan which includes a HM as preparation would help? The other way this may help is that you shift your focus away from the HM, as it sounds like you may have a mental block about running under 90 mins.
the "little more than HM" comment suggests you are running too fast, as your long runs should be at an easy pace. Have a look at the mcmillan pace calculator (mcmillanrunning.com), if you put in a recent race result it will give you a predicted marathon time and it will also give you a list of training paces based on your race pace.
NB the FM time it will give you will be more accurate based on an HM result than a 5k result etc, but is based on "equivalent" performance. If its your first full marathon the prediction will probably be a bit optimistic, as most runners will struggle to some extent in their first marathon over the last few miles.
I had this problem with a pair of Kinvara on one run, but realised it was due to my sock sitting too low on my ankle. It was easily solved by pulling my sock up.
Based on this, if your socks don't cover the spot where it rubs, I'd cover that spot with a plaster for a few runs. The repeated bending of the shoe fabric where it catches your achilles should soften it up and remove the problem. If this doesn't work you can then take the scissors to the top of the shoe to remove the excess material.