Working with influencers on commission basis (Affiliate marketing)

Our product is a childrens toy (0-12 years old) and our ideal customer is their parents obviously. I want to team up with mom influencers that promote my product on a commission/affiliate basis. Say I sell the product for $300 and gross profit is $50.What is the usual amount affiliates make on a sale like this? i.e. How much commission per saleThe customers should also have incentive to enter the code the influencer provides, so they should get something too. Again: how much? A reminder that our margin is $50, so we don’t have too much room.How do you make sure the influencers actually post about it? You don’t want them receiving your product and then doing nothing.Do you always have to give product away for free? Our product costs 300$ so we can't give our product away randomly to any and all influencers..How to ensure that customers cannot use the same code multiple times?As you can see I don’t have experience with affiliates that promote a product on a commission basis. Any and all feedback is appreciated. see hubwealthy.com/wealthy