>1) What is the limit on the string for the 1st parameter to SQLDAtaAdapter?

SQL Server's capability is rather large: 65K * network packet size (default=4K).

I'm not sure what the max. size of System.String is. I'll go out on a limb and guess that you won't run into any size limitations <g>

>2) Are there less 'round trips' to SQL Server if I combine multiple SELECT statements and delimit them with a semi-colon?

SqlClient should be making one trip to the server.

>I'm not allowed to use stored procs, ...

Why not?

-Mike