The letter from Mike Dinneen to Representative James R. Jones discusses two main issues. Firstly, Dinneen suggests installing a speed-limiting device in vehicles to address speeding concerns. Secondly, he urges Jones to vote for a cost-of-living increase in the G.I. Bill due to inflation affecting veterans and their families. Dinneen shares his personal financial struggles and academic achievements to illustrate the impact of inflation on veterans. He hopes that his letter will be helpful to Jones in making a decision on these important issues.