I am thinking of getting rose shrubs for the back of my garden. Here are the specs of my soil and garden:
Soil - Clay
Ph - 6.1 - 7.8 (based on what is successfully growing and blooming in the garden currently)
Moisture - Moist to very moist
Drainage - Poor to Fair (It's clay soil

Zone - 8
Location - Austin, Texas
Plant Successes - Oro Daylily (Blooming like crazy), Festiva Maxima Peonies, and Ornamental grasses
Plant Failures - Texas Green Cloud Sage (Ground is far too moist for them, the Ph requirements also state a higher alkaine type of soil...these guys died very quickly in my soil

Based on the above, are roses good candidates for my garden?
Here are the list of Roses I though of:
1. Knock-Out Rose
2. Sunrise at Heirloom Rose
3. Easy Livin' Rose
The three roses are compact enough to fit in my open area of roughly 3-4 ft wide. There are some areas in the garden where the open width is only about 30 inches. The tallest flower I have currently is stated to grow 36 inches tall (peonies). These shrub roses would be in the back of the garden.
Since I these roses would be mass planted in the back, I am planning to dig out a huge hole and ammend this part of the soil if need be. I heard ideally I should be digging a hole about 2-3 feet deep if I am to do this. The depth of my garden goes down about 5-6 feet deep.
Please let me know your thoughts?