Welcome to the family.
Great rate and, yes, credit is a big factor with State Farm, progressive and GEICO. It's bigger than your driving record (other than aggregious tickets)!!!!!
100/300/50 would be sufficient but for about $5-$10 more, having the extra $50,000 in property damage is better.
Just to clarify, the $5,000 in med pay pays for passengers of your vehicle and YOU if someone is injured or killed no matter who is at fault while occupying, entering into or alighting from an insured auto. It even pays if YOU are struck as a pedestrian.
What you were talking about in your original post is Uninsured Motorist and it should be equal to your BI limits. It pays for you and resident relatives of your household if you're injured and the at-fault party either has less than your 100/300 or is completely uninsured.