SOLID rock? That might be a challenge! My property is caliche and rocks myself, fortunately not very much solid rocks of any size. I've got some raised beds and areas where I've added a little bit of topsoil so I could grow some plants that can't tolerate my caliche. Look at this link, it has xeriscape plants for that area.

Here is a link that might be useful: Austin xeriscape

Welcome to Austin. What area of Austin will you be located?
I think you will love it here but gardening can be a challenge. This year has been mild but some summers are quite severe with lots of temps over 100 that really burn up the plants. Winters can get into the teens even tho the past few years have been mild with only a few freezing days. Get to know your native plants for the area--they can handle the variation best. If you will be west of I-35 the "soil" will be very alkaline. East of town is blackland prairie. You might want to visit the Lady Bird Johnson Wildflower Center and get familiar with the native plants--your best bet in this challenging area. Their website is http://www.wildflower.org and you can check out their database. Also, when you get to town, go visit all the gardens at Zilker Botannical gardens to see what grows here. For roses, azaleas and such you will need to put in beds with special dirt. There are lots of good nurseries here so when you get to town be sure to check out Natural Gardener, Barton Springs nursery, Marbridge, It's About Time, etc. Also Home Depot usually has a table of natives but also carry a lot of plants not really suited for this area.

Anne