You can certainly do it now while the soil is still warm. I don’t think you HAVE to prune, but it might make them easier to handle. Obvs add plenty of compost to the hole and water in well.

pruning by half would help prevent wind rock in the autumn and winter. as they are in pots you can plant them out now and any time up to the first frosts.

With roses, it's important to keep the grafting junction above the soil line. You don't have to prune it first, but pruning sure makes the planting part easier to manage - your less likely to get pricked.

Hi, I would plant with the graft union just below soil level, if you leave the graft above the soil, this promotes the growth of suckers from the roots, Derek.