Now I need some help from you super-fantabulous expert guys!!!

I have a loamy soil in my garden, but the problem is that the soil where I am going to sit my rocks on was lived by huge bushes that were cut down to the ground, although the entire root system was left underneath. These roots are almost impossible to pull out, if not really expensive. Can I avoid digging the soil if I already cover it with 2 inches of limestone sand (or granite sand, I still have to think about it) and topped with another 2 inches of 3"-6" colorado river rocks? I would put the moss boulders on top of this terrain.

Then off to the rock garden soil. Is this combination good for my rock garden (I will list the plants I want to grow below):
1 part of garden soil
1 part of peat moss
1 part of poultry grit
*(should I add 1 part of limestone/granite sand to it as well?)
Also, should I mound the soul before laying the boulders, or should I first lay the boulders and then fill the crevices with the soil?

Now, the plants I would like to grow are the following (still, I would like to know if these plants would grow on the south side of the house located in Dallas TX):

1) Armeria maritima 'Compacta'
2) Delosperma ashtonii 'Blut'
3) Ruschia pulvinaris
4) Alyssum montanum 'Mountain Gold'
5) Pulsatilla vulgaris
6) Dianthus
7) Phemeranthus (Talinum) calycinum 'Judith's Favorite'
8) Hirpicium armeriodes v.
9) Helianthemum nummularium
10) Aster oblongifolius
11) Hymenoxys scaposa
12) Saponaria ocymoides
13) Nananthus transvaalensis
14) Royal Candles Speedwell
15) Callirhoe involucrata
16) Zinnia grandiflora
17) Anacyclus depressus
18) Aloinopsis 'Karoo Red Mix'
19) Escobaria leei
20) Penstemon pinifolius 'Compactum'
21) Festuca tenuifolia 'Angel Hair'

Thanks for your time, really! I love gardening and I would like to make my house garden one of the future meeting locations of the Rainbow Garden Club of North Texas!

Rino