Welcome to YT!!
Well, what a clever way to teach him to poo outside! Good for both of you. I would strongly suggest you get Tyke on a regular feeding schedule. How old is he? Most people feed either once or twice a day. If he's still really young, you may need to feed more often.
Feeding on a schedule, you will learn when he needs to do his business. Mine run out and wee in the am, then rush into eat, then immediately after they are done eating they usually poo. I know this and I don't have to second guess what their habits are.
As for the chewing on the jeans, it sounds like you are giving him mixed messages. Let him know it's not okay, if you have to spray Bitter Apple on your jeans (make sure it won't discolor) and then make sure he has enough chewy toys or bully sticks. Is he teething? That may be why he's whining. He may need some hardy chews