I recently had a problem with my annotations being "lost". Solved it here
https://www.mobileread.com/forums/sho...89#post1826989
The interesting thing is, that the Sony device(s) basically only needs those adobe annotations, yet builds its own index (in database\cache\cacheExt.xml); maybe really just for performance reasons like cache suggests.
So in respect to any annotations except drawings (I think)...
for a) You just have to backup the annot files
for b) Just remove the parts the sony reader adds and copy the annot file back, named like the ebook file (which is only slightly tricky, because of calibre adding the numbering automatically)
for c) You could review/edit the annotations only on PC with Adobe Digital Editions (well, sure here it gets a little bit more complicated in regard to a) and b) with paths and consistency)
for d) The interesting question is if (many) other readers use different ways to annotate. Just in case it should not be a Sony specific solution only...
Hope I didn't miss the topic too much (?)