1: You CAN have UBoot with power kernel. You can even have it with PR1.3 patches. Matan already made a kernel like that, and it can easily be downloaded onto the device and flashed with the on-board "flasher" command with almost no effort.
2: You need to do the same thing to get rid of uboot. You download the fiasco image, and run the flasher (as per existing instruction in the other uboot thread and the wiki) - you don't even have to use a computer based one. You can flash kernels from on-device.
4. You don't need to swap SD cards or take them out to boot maemo. Yeah, booting with keyboard out is easier than taking out SD card. But loading with keyboard out, then selecting OS, vs loading with keyboard out and pressing any key, then typing the command to select OS, is almost the same. And you can do that easily.