Is there anything wrong with this understanding?
A few minor points:
Black-body radiation does not refer to a specific microscopic process, and in particular is not necessarily "the bonds between atoms giving off energy". Black-body radiation is an explicitly macroscopic phenomenon, whose usefulness comes from the fact that it doesn't particularly care about the microscopic structure of the material. For more details, see What are the various physical mechanisms for energy transfer to the photon during blackbody emission?.
Absorption and reflection are not the only things that can happen when light hits a medium. There is also transmission, for one. And in higher-energy cases, you can also have decomposition/photodegradation, ionization, and pair production, to name a few.
In addition to being dissipated as heat, electromagnetic radiation can also cause an object to accelerate or rotate, if the properties of the object and of the incident radiation are correct.
Why does infrared contribute so much more to heat than other wavelengths such as ultraviolet if it is all transferred to heat anyway?
Well, firstly because not all absorbed radiation is dissipated as heat. If the radiation is high enough in energy, it will break chemical bonds (like UV radiation) and/or ionize the atoms of the material (like X-rays) rather than simply increase the material's temperature. If the radiation is low enough in energy, it will simply be transmitted without interacting significantly with the material. So, in order for radiation to be primarily dissipated as heat, it needs to be around the same energy as a transition that won't actually break the material apart. Many (but not all*) materials have just such a transition in the infrared range, due to interatomic bonds having a typical binding energy of a few eV.
It also tends to help that, for materials around room temperature, the peak of the blackbody radiation spectrum is in the infrared range. This means that the amount of infrared radiation a body emits is correlated with its temperature, and in general macroscopic materials around room temperature will emit and absorb infrared radiation readily.
Of course, if you happen to know a lot about your material, you can use transitions outside the infrared to transfer heat. For example, water molecules have rotational transitions that are very closely spaced in energy; the energy difference between them corresponds to the energy of a microwave photon. So when water is blasted with microwaves, it heats up, which makes microwave ovens possible.
*For example, zinc selenide is effectively transparent to infrared radiation, so you'd have a hard time heating it up that way if you tried.