imo KSOAP is too much overhead. But go ahead if you like it
We have certain apps that offer an offline functionality by using persistant storage if no coverage is available, most don't because it is not really easy to implement.
good tutorials, hmm.
regarding a server application there are good examples about JDBC which can be downloaded together with the driver. the socket connection itself should be trivial.
i used the parameter-thing by URL myself. it works for small data but creates a lot of overhead and is quite slow.
if you want to work with SQL and especially want to get results back to your device you have to use a server.
feel free to contact me if you are interested in buying a general sql-bb-connector, i think we have that in stock.