A plant in a container can over heat faster than a plant in the ground. The roots cook in the container. Similarly, they get too cold in the winter. The ground, with mulch is reasonable insulation for a plant that just needs a little help to make it through. This does not work as well for a container.
Here is how I would handle this:
Now: Put the plant where the pot will be shaded from the sun from noon to 4, perhaps longer. OK if you need to prop up a tent around the pot. Grouping it with other plants in pots is another good option. Cooler roots is the goal.
Partial shade for the leaves during this hot spell is good, too, but I would find good bright light- perhaps partially under the shade of a tree. Full sun in the morning, bright dappled light in the hottest part of the day, then some more full sun late afternoon.
Every time you prune off old flowers use it as an excuse to shape the plant just a bit. Don't let it get too large.
Fall: Thorough clean up, trim it back a bit, bring it indoors to as bright a location as you can. Some roses can live as house plants, and do not need to go dormant. Most do need a dormant period.
Cold is OK, the plant should go dormant, just not as cold as your freezing wind could make it. Do you have an enclosed porch?
Winter: It should be dormant. Dark is not a problem. Late winter: you can un-pot it, root prune if needed, add fresh soil and a slow release fertilizer. Prune most severely now.
When you think there is only a few weeks until the last frost move it into a bit warmer a spot and begin watering it, 1 thorough soak, then see if there is a growth response and begin watering it as needed.
You can also begin moving it into the garden to a protected location in the warmest part of the day, bringing it in at night. Leave it out longer and longer as the nights get milder.
After the last frost date: If you have been moving it in and out it should be OK outside all the time. Until the weather starts getting into the upper 20s (C) or upper 70s (F), I would leave it in full sun.
