New growth on the Cramoisi Superieur should be quite flexible, so if worse comes to worst and you can't bend any of the canes, you could try cutting a few down to a point below fence level and training the new growth horizontally along the fence.
If the roots have gone through the drain holes, you're facing a couple of possible hazards. One is that the nematodes could start attacking those roots. As far as I know, there's no way to fight the nematodes other than planting roses grafted onto Fortuniana rootstock, which doesn't appeal to them or is immune to them. Another danger is that the roots could plug up those drain holes and water could collect in the containers. If this happens, you'll have to drill some holes in the sides of the containers, close to the bottom.
I'm an advocate of little or no pruning, but canes that attack people certainly should be pruned.
As for the fertilizer, I think you should ask that question in the Rose Forum. I've never fertilized my roses. I've never had the time to do it and I fortunately have soil that's good enough not to demand it.
