On the iss app is you look under the payment you will see your shop you completed, and what your payment will be. This will include any reimbursement that the limit of the shop is as well. When you first are to the shop that information is included who much is being paid and if there is any reimbursement and the max that will be reimbursed.

The self assign is how many you can assign yourself. Anything above that self assign limit, you can request and them it can either be approved for you to shop what you requested or they can decline. As you do more and gain more badges and reputation level you go up; your self assign limit will increase as well. I hope this helps.