Well, that's the price early adaptors have to pay. I'm really planning on providing support for things that are used, however (RP doesn't seem very used to me besides my own mods, which is why I'll gladly let it die/replace it). That being said, the recent change of
model_variants was quite a heavy one too - I would imagine that this is the worst that happens to Jelly stuff too (besides switching from Jelly to the official API, of course).
It's the fastest and for modding authors cleanest way currently available. For what you want to do, it will totally suffice - the examples that aren't working as you would expect are things like "I want to spawn clustered trees in the mountain", which the normal game doesn't either.
Hm, weird then. I've never had it happen to me with all the stuff I've made. It's true that SH.smod is heavily "bugged" from Jofferson's point of view; but all of these are orphaned, i.e. nothing points towards them so I doubt that they can cause any trouble. They're about as harmless as having invalid aliases in your mod that all point to non-existing files.
Depends on what you consider debugging information. You can turn on some loggers to get additional information and personally I'm using rp_console to test scripts/dump stuff, but that requires some lua and game knowledge.