for point 4, in displays you can set a smaller screen size, not just font to get it feeling more like miui. and from the homepage widgets settings you can set it to confortable, it will make the icons smaller... it's what i did when i switched from miui
for point2 it's been debated for quite some time... ended up catalogued as feature not bug, you want as much light as possible when using the torch so setting the secondn led makes more light. there's a couple of fixes available as zip files to change this behavior. btw, if you use the lineage downloader app you can flash deltas and auto add extra zips to flash, such as custom kernels or extra fixes that aren't built in. pretty nifty that!
for1 try updating to the latest firmware:
https://xiaomi-firmware-updater.github.io/downloads/ careful to always pick the mido one! global when available fw_miui_HMNote4XGlobal_8.2.8_3ff3a578bf_7.0 is what i have.
always backup first!