Veterans blood type

The blood type is part of his military medical records, however, the VA doesn't keep samples of the blood around so you couldn't use it for establishing paternity.

How could i found out if i where listed on any insurance claims that were made at the time he was living

You'd have to find out what insurance agency (preferably the agent involved) and see if they can pull up records. However, there will be some privacy concerns in that regard. You'd probably have to file with a court for release of records.

Having a blood type is only a probable way to determine paternity. You have to have all three types for a possible match, yours, mom and dad. DNA is the only true method. If you can ask a member of his immediate family for a sample, it would get a 90% probability. You might be able to get a court order to compel or even exhumation but you need a bunch of evidence to get a judge to agree with you. Knowing who your parents are is one thing but how old are you and is there another reason to determine paternity - money, status, etc? Remember if the man is dead, you got to know your treading in unchartered waters. Be careful.

The VA will forever have access to the veteran's DNA.