That is odd. When you ran reform-emmc-bootstrap it should’ve printed a warning but otherwise should’ve offered to flash u-boot on eMMC. Did you take this offer or did you decline it?
Yes, the risk exists. But unless you flash an unknown u-boot binary or loose power during flashing at a very bad moment, all should be good. Flashing u-boot to eMMC using reform-flash-uboot has been successfully confirmed to work by multiple parties (including myself). I am booting my A311D classic Reform with u-boot and /boot on eMMC and do not need an SD-card anymore. In fact, this has already saved my butt because I temporarily had my sd-card reader broken and had that persisted, I would not’ve been able to boot my machine at all (luckily I was able to fix this issue with the help from minute by bending some of the pins back again).
That is possible and I have been doing that for a long time before I switched to having u-boot and /boot on emmc.
No, they are not. They are as outdated as the instructions in Howto: Upgrade an existing MNT Reform system on encrypted NVMe for RK3588 So I now added the same disclaimer to that article. Though in principle, if you want to do things manually, then yes, the instructions are still okay in general.
Are you booting with a HDMI display attached? I haven’t seen this problem with my A311D classic reform yet but I’m also still on kernel 6.12…