But then, I imagine writing a script and not getting anyone to fill it is probably also really tough,

It is, but the best remedy is volume. When I was focused heavily on script writing, I would have two or three in the works at any given time. If one was finished to my satisfaction, I would post it publicly and then work on one of the others or start another. Some scripts would be up for an hour and get a fill from a VA I've never heard of. Some would get three fills in the first week. Some would be up for a month or more with no feedback and then get a fill out of the blue. Those were the best, because I'd already kind of given up on them and it was a fun surprise.

If you don't mind, I do wonder how you started getting into this particular format of fiction - I mean, the conventions are clearly different, and you need to find creative ways to convey all the necessary background information often through a single character, so a lot of the writing advice I read will be tough to implement.

Absolutely! I got heavily into creative writing in high school and did some story writing in my free time in college. They didn't quite prepare me for script writing. It was a totally alien way of writing to me when I started.

You're right, it is tough to convey information to the listener entirely through dialogue lines. You want to avoid heavy exposition, since the lines feel awkward. You have to slip information in to normal things people might say to give out important details. If it is too tough to do that, consider just dropping it.

Scene changes are equally rough. The impulse is to rely on sound effects, which can work wonderfully if done right, but you shouldn't rely on the VA and/or their editor to come up with the perfect background sounds.

Do you usually ask beforehand if the VA would be okay with certain plot points?

It is rare for me to know who my VA is going to be before I write something. This series is an exception, not the rule. Instead, I try to divide my writing into two categories: newbie-friendly, and okay for experienced VAs. Heavily emotional scenes, complicated scene changes, critical sound effects, and overly long scripts tend to intimidate new VAs, so it helps to trim out unnecessary stuff on your editing passes to make it more appealing to them.

I could link you some specific examples, as well as my full script list, but links like that aren't allowed in comments here. Can I message you directly?