Execution of multiple sql queries using c# WPF app

I am writing a system utility similar to management studio with c# and ado .net with mvvm.

basically I have a UI similar to the query execution windows or the former query analyzer

any query can be typed in a text box including  multiple queries.

I have to execute multiple queries if they are selected together and have t0 present resultssets of each.

Any database or table on the server can be mentioned.

I have to make decisions on achieving best performance.

1. how to make use of connections and threads when executing multiple queries.

2. is ado .net or linqtosql the best way to do it

3.i have placed only server strings in app.config and rest of settings in my own static app.settings class. 

4. is putting DAL in model ok since domain logic is absent here ,as it is a system utility?

any recommendations on the above?