Workers Comp is different in every state. So I will tell you what I know about TX workers comp. Workers comp gives you life time medical on your knee. 20 yrs from now if your having problems, workers comp will pay. They also pay all medical bills that you have right now. You didn't say if you were on state workers comp or private workers comp. My husband is on private workers comp. When the Dr says its time to go back to work, he will get evaluated, his final check will be based on his impairment. Say the Dr says hes 25%, the insurance will figure it like this. 25 X $336 (his weekly check) You can call you adjuster and ask how they base your final check. Since your Dr says you wont be able to go back to your job, you should contact a lawyer. Hope this helped a little.
First of all, you need to cover all your bases before taking legal action regarding fathers' rights.
From what I've read, your son is safe from statutory charges as she is 16 and he is not 19 or over.
Have you already taken the step of talking to the girl and letting her know how important it is that your family name also be on the certificate. Don't do it an angry, pushy or rude manner. Talk to her like an intelligent person and try to come to a compromise, such as hyphenating both names. Let her know that it could cause difficulties in the future or embarass her children when other kids ask "Why don't you and your daddy have the same last name?" Also make sure that she knows your family/son will be there to support the baby and her efforts forever. She may feel like she is doing this alone, and thus wants to get the credit for it. If she felt as if your son and family supported her pregnancy (parenting classes, family activities) she may be more inclined to listen.
If none of this works and she will not listen, and your family/son is taking responsibility for the child, you have legal options. (see the third link). If she acknowledges him as the father on the birth certificate, he has a say in the name. If she doesn't acknowledge him on the certificate and you can prove that he is acting responsibily and is the child's father you can get a Court Order of Parental Responsibility, which will then give your son the ability to add his name to the birth certificate and alter his baby's name.
There are many details and nuances to these laws and may vary in Minnesota. You'll need a lawyer if it comes down to it. Oh, also, make sure to keep detailed records of visits and monetary support (write checks or money orders and put information in memo lines) so that if it comes down to this or she fights for custody in the future, you'll have proof that your son or family is supporting the child both financially and physically.
But lets hope that she'll understand where you're coming from and you have a great familial relationship!