OK all my green-thumbed friends, I need some gardening advice. Here's my backyard:

I have this hill of rocks that I threw wildflowers seeds all over when the snow finally stopped late Spring. Now I have a bunch of things growing, but I don't know if it's weeds or flowers. What seemed like a great idea is not turning out to be such a smart plan. However, I do have a few flowers starting to bloom.

Cute, huh? They are pink, purple and white. I have several patches now in bloom. Fun!
Although, this is how most of the yard looks.

And that's after pulling what I know are weeds. (My mom informed me what I thought were poppies were actually weeds, sad.)
Here's my biggest problem. We planted 4 rose bushes. Two are looking good and two look like this

Help. This rose is called the Ingrid Bergman rose and is a beautiful deep red. I don't know why the leaves are turning brown. Do I need to water more? less? fertilize? pesticide?
This is our other problem area

It's very sandy soil that is eroding away from the rocks. (One rock actually fell and rolled into our house- it may stay there and be landscaped around, as it is extremely heavy.) I heard that day lilies do well in sand and may help with the erosion. Any other ideas?
This is my favorite part of the backyard. This tree was overgrown when we bought the house. (It was a rental and the yard was in bad shape). We trimmed it up and now it hangs perfectly over the lawn to provide a little shaded area. I planted some bright orange flowers beneath it that have done very well.

This is another tree that we have pruned. It had branches growing along the ground and huge thorns on it. Rick and I were scraped up for weeks (worth it). We still have a little pruning to do on it, but it may wait until next year. We now have to figure out what to do with the hillside. I'm thinking a hardy ground-cover.

So there it is. I'm up for any advice/ideas.