No really. The rules in this forum don't allow it.
As for how to deal with proofing, you can't make someone do something they don't want to do.
If your clients are signing off on errors because they can't be bothered to look at the proofs, what can you do? <shrug>
If they aren't getting back to you, a nicely worded email and PHONE CALL saying they will lose their production slot and will not be rescheduled until some response is received, along with suspension of due date, and in extreme cases mention of breach of contract, also sometimes works.
The reason you have a contract spelling everything out is for just such occasions.
The reason you get a deposit before work starts is for expenses incurred up to the point of failure to communicate.
If you've run a print business you know this. You should also know standard markup of product.
As a freelancer do you have a tax ID and are you able to collect sales tax? If so, you should be working with your printer on a resale discount. You may not have enough work to make it worthwhile for them though. So you are stuck with less of a markup until your client base warrants a larger one based on more wholesale product purchased.
Or simply charge all the market will bear.