Congratulations! You might consider using used bricks or stone, concrete blocks work, too.

I started in clay, cliché, don't worry about removing grass, clay rock anything. Either law down cardboard, landscaping fabric, or news paper, or junk mail cover it up with mulch, more dirt, compost. etc. start planting on top of it. eventually the clay will break down with roots, and became beneficial. good bugs will break down everything and make your dead soil alive. You can watch permaculture video etc. What type of rose you have, real roses or even the pseudoname roses like rock rose etc stay just fine in clay soil. I grow food, so I grow real roses, and aside from rain water I don't even water. My clay soil hold water for the hot summer day of texas for my plants. I harvest a lot of food, more than I can consume.

I know a lot about red clay. It's dead soil. My best suggestion is to put down a heavy cover of straw and leaves. But you need to put that in an area you're not going to be working for several years. You can add more to it over time as it decomposes. That will start the benefical microbes and critters working. Throw a small box together for compost. You can either work it or let it lay. Either way it will decompose into beautiful rich soil.

As for concentrating on just one bed at a time, that is prudent, but having waited many years to finally have a permanent home, I have the urge to quit my job and do nothing but garden nonstop! Lol
I am focusing purely on the front yard this year. The back is bigger and entirely shady, a whole new learning experience.

Congratulations on the purchase. You now have a "hobby" for the rest of your life.

The timbers really do not in a few years. I am in Ohio, and they rotted too quickly. I think they only lasted about five years at the most.

I have heavy clay soil and I added a lot of sand to my beds and compost to them and rototilled it in, this has really improved the soil. Making a border with retaining wall stones as Cast 1es suggests would last as long as you're alive, stones or old bricks could also be utilized and can be had for free if one uses a bit of ingenuity and elbow grease. If you have even a little bit of slope a french drain can be installed from the raised beds to a low point to assist with drainage so your plants don't drown in the spring rains.

I live in coastal NC with the same problems .too wet in the spring and too dry in the summer . Six inches above grade is fine for my vegies I don't know about roses .

Congratulations ! Do hope you checked to see that yours is not in the flood zone , before you made your purchase . You might consider limiting this year's efforts to just one garden . I'd recommend investing in the , " castle stones ," Yes , they're more expensive than the treated wooden landscape timbers , but if properly compacting the earth before you install them , they'll last for decades , and you can stack them , so you can raise the beds by adding a second row of stones on top of the first . Good luck hon , Remember a new home is always a lot of work , so don't take on more than you can handle .

Congratulations on the house!

Here in New England I don't have those issues - but I'm sure someone with knowledge will be along.

The one plant I brought from my old home to my new one - was a rose bush.