To add more items in item mall is on your cash.sdata, you can use ShStudio to do this, that is the easiest way as you do the changes and it will generate the sql query needed for this so that you just need to run the query on your SQL server and it will be done.
As for the exp, you can go and do it manually by updating every exp field for every mob on your database or go on the server mgr > game > commands and type in /exp2xenabled [amount] in which the amount will be the exp rate you want.