2.)linux kernel do the same thing than any other kernel API/ABI cycle, linux is just much faster in its release cycle than the others.
3.)thruth be told packaging blob drivers is distro responsability since no one in kernel.org expect ppl to use the great and latest without a very high technical level to begin with.
4.) distros problem is that is really hard to package this blobs correctly[even when using an LTS kernel] due to their alien nature against the OS, so most of the time this frankestein breakage arent actually kernel changes but the packages breaking or users trying to get the latest drivers from external sources due to the distros slow updates for blobs that normally ends badly.
5.) sure there are ways to improve the situation like modularize the kernel [drivers and kernel] and provide an intermediate API between drivers and kernel. in fact you can even fix some issues allowing userspace driver[bluetooth, usb, i2c, pmbus, any low bandwith/latency hardware/sensors]/ kernel drivers[sata/GPU/Raid/scsi/vritualization, the big fat boys] and hybrid drivers[input/dvb/sound/etc] <-- is a titanic job but can be of benefit for stuff like security and stability and if done well drivers API/ABI stability for longer periods of time