Louis is a cutie! Welcome Joy to YorkieTalk, it's good to know people learn a lot from this site, it's what it was created for!
It looks like you've done some great training work with Louis so far! Especially since he is only 5 months old! For training on pee pee pads, dab a bit of his pee onto the pad at first, then get him to associate the pad with peeing. If he can pee on command, let him sniff the pad next time he needs to pee, and then command him to pee there. It'll take a bit of time, but I'm sure he'll get associated with it soon enough.
Have you read about Junebug's BANG! trick with Otis? It's definitely one of my favorite tricks of all time! And simple to train! :P
http://www.yorkietalk.com/forums/sho...highlight=bang