That seemed to be a valid link to download, although it needed to be clicked as an external link.
I occasionally had the wifi not work. I just restarted it, and then it fixed itself. Then on times it didn’t activate, again, I just kept restarting it till it did work. This was for an earlier version that I fiddled with a lot.
Just having a think, re: the slow downs. Perhaps it’s taking up extraneous memory, trying to get the wifi started with some kind of cyclic loop.
Another thought. Dimming of the screen could be happening after initially starting, and then applying the setting you have in your system. It boots up at 100% brightness, which quite frankly is way too bright, and drains the battery like mad. As for why it can’t be changed, maybe it’s the wifi loop taking up too much memory, not allowing the hook for brightness adjustment to activate.
Have you tried flashing to a different card? Sounds like there’s a lot wrong, that could almost warrant starting a new thread.