Don't get discouraged about starting up with 4e instead of 5e. There's not so much to track during the early levels. It will work best if you have a battlemat or some graph paper for fights. Update the monsters as Snoof recommended. If neither of your players is interested in a healer, instead of a Cleric give them an NPC Warlord who provides healing and gives the PCs extra attacks with powers like Commander's Strike (in the PHB) and Direct the Strike. This NPC won't distract you, the DM, from running the opposition in a fight because it's so low-maintenance. Don't worry about the details and have fun with your boys. And welcome to the forums!