To your first: STORE always replace the old file with the current table you are storing. However, you can always do a load of the existing values, then load the new ones, then store them into the same QVD, so it will keep all files.
Customers: LOAD * FROM Customers.qvd (qvd); // This loads the already existing records in file CONCATENATE LOAD *; // This will append to the Customers table the following load SQL SELECT * FROM DataSource.CustomersTable; STORE Customers INTO Customers.qvd;
To the second, yes, it's possible, although you will need some macro code and loop to load those tables. Check this post to see how that looping may work and if that helps.
Hope that helps.