How much cost error rate from Amazon’s actions should a new seller plan on?

I’ve been researching selling on Amazon for a bit now and it only seems normal that I should go ahead and plan on them abusing me and making errors that cost a new seller.

So this actually is a legitimate question and I would like some examples or strong suggestions as to what I should calculate in. I’m sure the percentage/amount is small, but by this point I think it’s only to be expected. I also imagine they continue to change their rules at their own convenience as they move along. Is that true also?

Furthermore, is this a good time to just go ahead and sell a product (mine would probably be low cost around $13/unit) at a loss just to go ahead and gain market traction. If a new seller is encountering loss from one end by Amazon’s practices then why not go ahead and just up the game and sell the product for less than you paid (need) for a while and take a loss on each unit in order to get the product/word out there?