thanks you too

No.

For 2, I'm not certain about this but it appears to have to do with the number of possessed who are still alive after the first glory skip. You'll see in a lot of fun people use the rocket launcher to kill several of the possessed, which in combination with reloading the checkpoint after blowing up the barrels seems o effectively prevent the softlock.

I had that issue once too. I did a bunch of stuff, nothing worked then I shut off my computer and turned it on the next day and it worked. ¯_(ツ)_/¯ I don't really know what to say but I guess you can try just waiting.

I've been doing a handful of ils, but haven't done any longer levels yet (mostly because I'm too lazy to actually get a 100% save) but I'm wondering, are loads in il runs timed? In a lot of older runs I've seen people timing loads, but since there's a loadless timer, do I still have to time loads?

Make sure you're using Vulcan, all lowest settings, etc. Doom is capped at 200 on pc, 60 on consoles. The tool made by instagibz also massively boosts your framerate, but if you can't get past 69 at all it probably won't be enough.