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Since it has been composted, yes you can. With any new amendment, I always advise to use it on a few roses first and see if there are any negative effects. That way you are not dealing with an entire rose bed of negative issues. I doubt that you will have any problems though since it has been composted.

You don't say what kind of roses you have, but since you are in a warmer zone (10), your roses should be fine. You will notice the author of the articles below lightly prunes his roses in the fall after they go dormant, then again in the spring.

The spring pruning is especially for zones that have sustained cold during the winter and the roses experience dieback that needs to be pruned. A hard pruning also increases vigor for spring growth.

https://www.gardeningknowhow.com/ornamental/flowers/roses/pruning-roses.htm

https://www.gardeningknowhow.com/ornamental/flowers/knockout-roses/prune-knockout-roses.htm

https://www.gardeningknowhow.com/ornamental/flowers/roses/roses-winter-care.htm

I'm going to say sawflies because of the whitish looking damage to the leaves. Sawfly larvae just eat the top layer of the leaves. You can use insecticides such as horticultural oil, insecticidal soaps or neem oil. Do not use Bt as it will not work on sawfly larvae, which may look like caterpillars but they are not. If it's not sawflies, those insecticides should still work.

https://www.gardeningknowhow.com/plant-problems/pests/insects/sawfly-insect-control.htm

It looks like shipping damage to me. Sometimes folks are not real careful with plants when loading them or unloading them for sale at various stores. If you happen to buy some that are new arrivals to the store, you do not see the damage done yet. If you can get a product called Super Thrive, I would buy some and put that in their watering water the next 3 to 4 times they need watering.

Sounds like you have a shrub rose and some climbing roses. It's too late now to plant as they won't get established before freezing. Keep them in a cool place and water sparingly during the winter. The roots should not be exposed to the air. Go ahead and plant them in pots for the winter.

I would be suspicious whether you really have midnight rose seeds, especially since no instructions were included. I couldn't find a reputable resource online that there is such a rose though there is a coral bell plant named Midnight Rose.
So there is no telling what your seeds will produce. If it is a rose, here are instructions for growing rose seeds:
https://www.gardeningknowhow.com/ornamental/flowers/roses/growing-roses-from-seed.htm