I am hoping some sellers can help out with this process as it is not super clear from what I can read in faq's, etc and customer service didn't really seem to know the answers either. Some background:

We are a small family seller and manufacturer of 2 skus. For years we had our original sku only FBA and due to rising fees, customer complaints of orders getting smashed (shipped in bags instead of boxes) and we launched our own ecommerce website. We ended up switching that sku to FBM and sales have gone down as expected, but profits were in a better place. When we launched a new smaller sku we only did FBM. We are considering doing a test of FBA on that smaller sku due to better economics and a promo offer Amazon is offering to do so. If the test does not prove effective, we would switch back to FBM. So here is our questions:

Is it better to switch this FBM sku/asin to FBA or create a new listing and either keep both up or then hide the FBM one? Related question 1- if we switch the same one, can we switch it back? Related question 2- if a new listing, is there a way to duplicate the listing so we dont have to reenter all the info? Related question 3- If I create a new listing, do we need the added expense of putting different lables on the boxes for the new listing?

There does not seem to be a way to create the FBA listing using the existing one because there is a chicken or the egg situation where I can't send inventory to amazon without an FBA listing and if I switch it seems like it would kill the FBM listing immediately so I'd be left with weeks of no sales until the new inventory can be shipped, received and available for sale via FBA.

Does anyone have any experience or recommendations of what to do here?