Answer: Bare root (soil-less) roses are planted in very early spring as soon as they become available. Potted roses can be planted any time the soil is workable, but early spring is a good time, as is early fall.
There are many types of roses and there are as many opinions about them as there are rose growers. In my experience, the most reliably hardy roses are grown on their own roots instead of grafted and should be rated hardy for your winter zone.
Since you are so interested in roses and will need to evaluate your soil and growing conditions as well as prepare the soil and select the plants, you might want to read up on roses a bit.
A book I like is "Roses for Dummies" by Lance Walheim, ISBN:0-7645-5031-4. In it you will find straightforward answers to all of your above questions plus lists of suggested types of roses for different situations as well as selection, planting, and ongoing care instructions. There are also lists of recommended varieties for attributes such as fragrance or color.
Enjoy your new rose garden!
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