I have heard that you can turn your wife into a vampire, I was wondering if you could turn other NPCs as well, if so does anyone know which ones?

Yes you can turn other NPC's into vampires. It's a side quest, there specific npc's but its glitched and when you keep doing side quests you'll end up getting those quests again and you can't complete it cause they are already changed into vampires, easy way to get around it is to kill them (though you will fail the quest but it doesn't matter, just go back and talk to someone for more help and yeah they'll give you another quest)