1. Not all devices officially support these features. If you don't see these features, then very likely fuxi doesn't support them.
2. Ask Xiaomi why they didn't include new Gallery app in Global ROM till now.
If you installed ROM from fastboot, very likely you don't have TWRP. If you don't have TWRP, then OTA won't work. Install TWRP or flash it using fastboot.
Make sure you actually downloaded reuploaded build by checking MD5 (d089d0de3cd76cb063b06fc000087c54) or SHA1 (f6b5e711475355580b219a12ce1c079f648edd87) checksum. Sourceforge sometimes caches old builds.
You "can" unlock your phone, but in case of CN versions you must have Xiaomi Account with China region and Chinese Xiaomi Community permissions, which require ID verification and pass an exam. No go for most Global users.
1. Xiaomi checks them differently in Global ROM (and our ROM is being recognized in code as Global ROM). Patched for next release.
2. "ability to customize them" - explain, no idea what do you mean there.