thank you, i am VERY excited about this...as a user with an 800+ title Calibre library, i was very disappointed when i realised calibre cannot connect to MTP devices
i have some thoughts, if i may?
-paid apps often have greater success when they also have a free counterpart...if you can figure out a way to disable some functionality for a free version and get people using the app, you may find that more will upgrade to the full version...it would also bode well if your app shows 50,000+ free installs as opposed to only 150 paid installs
-metadata - when syncing calibre to a proper ereader (like a Sony) any changes made in calibre after the book was added would also be updated and synced...currently, with no syncing capability for MTP devices, books with changes need to be converted over themselves (i.e. epub to epub) so any metadata changes are saved and visible on the android device...is this something your app may be able to address?
-Aldiko - you mentioned aldiko...though of course it is a very popular android reader app, i would be surprised if many who use calibre would prefer aldiko...when i last tested it, upon importing my books into aldiko it messed up ALL my tags and added a lot of superfluous crap...anyway, that's just an observation and quite off topic
your questions
...Question 1: would you prefer that we released ASAP...
ASAP, always asap

content server functionality would be a great added bonus, but this is already achievable via other means*, whereas syncing is not (*i currently have a no-ip setup and access my library via a standard http address, or via my ereader app as a 'net library' - that's just one example)
...Question 2: connects to public wifi ...
no
...Question 3: more than one computer running calibre...
no