Nope, sorry, not a baylor student. But if I was, yes, I think it would prepare me well as baylor students finish their preclinical year in 1.5 years so have additional time to do research if they wanted to...which is key for rad onc. But someone from baylor might have better input...
As for the difference between those specialites; I will only say that radonc is very different from the others- people hear "rad---" and assume the three are related. I will stick with rad onc: its bascially being an oncologist who treats with radiation. Its technique oriented more than medonc. medonc uses a lot of supportive measures while adminitering chemo; rad onc will do some of the same but is more involved in approaching the treatment of the patient in 3D space the way a surgeon does: look at the anatomical location, take into account info from surgery, pathology, normal tissue location, volume, etc and then plan. also order approrpriate further diagnostic work up. Sorry for the plug here but i wrote a chapter on this in the text "Ultimate Guide to Medical Specialties" by Freedman (Ed.).
The confusion stems from the fact that the specialties of radiology and radonc were originally one. In the past, physicians trained in the use of radiation for both imaging and treatment and called themselves radiologists. A specialty board (the ABR) certified radiologists.
Over time (c. 1950s) it became clear that diagnostic radiology (originally just x-ray diagnosis, now the use of imaging technologies to diagnose disease, including X-ray, US, CT, MRI, and nuclear imaging, as well as related radiographic-guided procedures) comprised a very different body of knowledge from "therapeutic radiology" aka radonc (the use of ionizing radiation in the treatment of cancer and other disease). Interestingly, to this day, the ABR certifies both rads and RadOncs (but each are elegible only for their own certificate).
Interventional radiology is not a separate specialty, it is an offshoot of diagnostic radiology. Certain procedures (like angiography, US-guided biopsy) are naturally performed under imaging and for various reasons have been developed and performed by radiologists -- these procedures range from simple things done by most general radiologists (perc nephrostomy, US-biopsy, -thoracentesis etc.) to specialized procedures done typically by fellowship trained interventional radiologists. Certain other physicians (surgeons and cardiologists) also do interventional procedures (though not as well - just kidding!! no I'm not...)