Yes, you can prune them but I would wait until the plant has gone dormant to prune that much. Most of the time though, people prune them in thirds (1/3 per year). However, with the plants being a safety issue on your pathway, I would cut them low whenever it starts snoring away. It will be less stressful for the plant that way. If your winter is dry and the soil has not frozen, water it some once every 2 weeks or so as pruning & coastal weather can wake it up (but hopefully not for long periods). Do not fertilize again it until Spring 2014. If the problem is severe enough where you CANNOT WAIT and HAVE TO prune now then go ahead but (a) try to keep the soil evenly moist, (b) maintain 3-4" of mulch up to the current drip line and (3) monitor the plant until cooler tmeps arrive and (4) do not be surprised if new stems generated now die over the winter.

Well, there is still a chance that they may survive but we will not know. They are definitely suffering from transplant shock and a little from the high temperatures (35) in Australia this time of the year. High temps will cause the leaves to limp as in your last picture although lack of water will do the same. The main cause of the problem here is that part of the root system was cut during a hot part of the year and what is left of the root system may not be able to support the growth above ground. I would plant the hydrangeas where you were planning to put them. A location with well draining soil & morning sun (or dappled sun) will be fine. Then mulch them with 7.5 to 10cm of any kind of acidic mulch. You need to keep the soil moist as much as possible without making the soil wet or dry. With plants that are this stressed, I would do that manually instead of watering every "x" number of days.... Insert a finger into the soil to a depth of 10cm and only water if the soil feels dry or almost dry. Write down in a calendar when do you water them. After 2 weeks of doing this, observe on the calendar how often you water and set the sprinkler to water 3.75 liters on that same frequency. Wait one week. Then look at the plants again. See if any of them have improved. If one of them has not, prune off maybe about 1/3 of the stems on plants that look bad, like the one on the top photo. I think the plant on the last two photos may not need to be pruned and could recover with enough moisture. Do not apply any fertilizer or coffee grounds this year. Just keep them on water or some liquid seaweed.

I'm sure that your plan will work with that particular type of winter protection. Give it a try...they'll well worth your effort. There are so many varieties out there to choose from and so many colors.

" The endless summer varieties like the Summer Crush are bigleaf, correct? Seems like a lot of mixed reviews for those on here. " They can be tricky but most of the issues are with the first ES introduction, Endless Summer The Original. I personally grow Bloomstruck and it is a nonstop performer in my garden!! But there are a whole bunch of other new and old growth flowering macs on the market that seem to have a better performance record. If you really like some flower color, I'd consider 'Pistachio'. A stunning combination of lime green and fuchsia pink with blue and purple highlights: It is a very heavy and reliable bloomer in my garden.