To answer the 1st one, using the database way seems cleaner, as u only enter it once.
Popups of matches may happen for every show you drag in. Like this 'Lost' tv show search.http://www.thetvdb.com/?string=lost&searchseriesid=&tab=listseries&function=Search
Secondly, the AirDates and Absolute Numbers method uses a different way than the normal SE/1x1/101 way.
It load a xml file for that show which contains all the tv data.
SE/1x1/101 way just loads the webpage itself.
Could be many reasons why it seems unstable. Maybe when the XML download starts, it uses a cache file instead? I'll see if I can avoid a cache file.