1. https://sourceforge.net/projects/xiaomi-eu-multilang-miui-roms/files/xiaomi.eu/MIUI-STABLE-RELEASES/MIUIv11/xiaomi.eu_multi_HMNote9Pro_HMNote9S_V11.0.10.0.QJWMIXM_v11-10.zip/download
2. Miui versions
3. No
4. Hmmm, I found the phone quite useful, don't know about that... It is faster...