As you know the values passed as parameters have a significant impact on execution plans. I read somewhere, that when a query is compiled in a stored procedure, the...

You could have got the correct result if you placed a GO between the Alter and the Select as well. The Alter had to be executed in a batch...

What will keep your transaction log small is running Backup Log every 2 hours. The WITH INIT, NOSKIP has no impact on the transaction log size. WITH INIT...