What are some characteristics of venules and arterioles?
I think this question is a bit too broad to write a comprehensive answer to, and there will certainly be some variation between tissues.

However, here is one reference that might give you what you are looking for.

I used to make acrylic arterial casts, mostly of coronary arteries but also some dabbling in the pulmonary, renal, and hepatic systems. My experience with the coronary system is that most of the arterioles come off in a tree-like branching pattern from quite small arteries, but there are always exceptions. I think the "fuzziness" you refer to definitely depends on the scale of observation: the further away you are, the more "fuzzy" arterioles look: of course they will never be as "fuzzy" as capillaries, but certainly once you enter the muscles themselves there is a lot of branching, but that branching isn't necessarily uniform. That is, there may be larger branches running in one dimension, and smaller branches in another dimension.

In larger vessels you also have the vasa vasorum: arteries that feed the large arteries and veins themselves. Some of those vessels are certainly the same size as arterioles, and some branch directly off the main vessel, but I am not sure whether anatomists always consider those to be arterioles or if they are considered separate.

From the perspective of interventions such as surgery, etc, smaller arterioles aren't really any different from capillaries, and larger arterioles might need to be clamped off or cauterized, but there isn't really any way to avoid them if you are cutting into a vascularized tissue. One wouldn't avoid these vessels they way they might avoid larger vessels.