I hope you put mulch around your rose to keep the water in the soil and the weeds down that compete for the food (fertilizer) and water. Do you have the name or tag still of your rose? Be sure to remove spent flowers at the 5 leaflet point and always remove to an outward facing bud. You want your rose to be V shaped and allow air into the center for good air circulation (cuts down on fungal diseases). Be sure to remove any crossing or broken stems especially if they are in the center of the rose bush.
Make sure to feed organically with a fertilizer specifically made for roses like Espoma Rose Tone. Get some Epsom salts too and apply in July around the base of the rose (about a half cup worth). Roses take a lot of magnesium out of the ground and the Epsom salts replenish it and the rose uses it for basal canes and bud growth. Seeing you are in Texas I suggest you contact your local cooperative extension (Texas A & M is your land grant research College/University) for further advice re: when to prune back winter damage and when to start and stop feeding your rose bush. Where I live, once the roses leaf out completely, we give them an initial does of Epsom salts and their first feeding. We feed roses monthly when they are actively growing (from April to late August by us). We stop feeding in September and stop deadheading or removing spent flowers by October. In October we no longer deadhead or cut the stems (canes) but we just take our hands and remove the flowers off of the stems. This signals to the plant to start going dormant.

Here is a link that might be useful: Texas Cooperative Extension Counties Link

The blooms that were on it at the store were probably set in cooler conditions or in a greenhouse. That's why they were larger. Now that it's getting hotter where you are the blooms will naturally be smaller in size. The heat is probably also why the edges look a little burnt. Roses love sunshine but are not fond of high heat and will burn.

Without seeing a picture of the leaf damage I can't say what is eating them. Try blasting the undersides of the leaves with a hard spray of water and see if that helps. The yellow leaves at the bottom could just be old leaves that have served their purpose and are no longer feeding the plant so they die off and the plant sheds them.

Keep it well watered and when it starts to get very hot find a way to shade it. Even a lawn chair over it to keep some of the sun off will help.

If there is new growth you can go ahead and fertilize it but be careful. You don't want to burn it further. You can use any good balanced fertilizer, dry or liquid, organic or not, but maybe just start it out at half strength. Be sure to follow all other directs carefully. Water the rose before fertilizing and then again afterwards. Water helps the plant take up the nutrients. Do not fertilize if temperatures are above 80 degrees. Do it early in the morning or in the evening when the sun is less strong.

Roses are amazingly resilient and want to grow so most of all fret less and enjoy more!

As Seil said, this is probably transplant shock involving stronger sunlight and maybe disturbance of the roots. All you need to do is keep it watered but not saturated. In moderately warm weather, I water transplants thoroughly every three days. Fertilizing makes it harder for struggling plants to take up water.