With regards to importing my old db, regardless of which version I've tried it always fails.
I have the latests version 1.37b unpacked to a clean directory, then I copy 1.37d xls file into the same folder.
I then change the name of the 2 station db file to be the db I want to use
TCE starts with the 2 station database and appears to function fine.
Then going to Options locating my personal db and running the import results in the issues that have been mentioned previously. As per this
posting.
UAC is deactivated.
Therefore I resorted to copying my old TCE.mdb over the top of the new db and copying the changes directly into the Access db file, these being the new Military economies and the Unsanctioned Station.
Looking at the differences between both files apart from my station data everything else looks the same, in that it has the same number of rows for all tables in Access.
Fortunately this method worked for me, but I'm concerned that if/when you change the schema for the db or change it in a big way my db won't work and I won't be able to import it.
I've now got very paranoid I'll lose my saved station data, so I'm being very meticulous with saving my own backups on a regular basis, in fact I backup the whole of the TCE directory, just incase.
At the moment I'm still able to use TCE with my own db after the above manipulation, but I'd like to be able to import it via the correct method and not have to edit the Access file, as although it looks fairly straightforward to do that, I'm sure I could break it quite easily without knowing really why.
TL : DR 
I've read all the issues others have had with importing there db into TCE and tried all the other methods you've stated, nothing helps with the import I still get the same errors each and every time.