2: Replace them with avid tes fan modders and Modders from other games that are also Tes fans (The lore friendly ones by the way- im going to punch someone if i find a holy gold daedric currias in a tes game)
3: pay them and give them some extra money for extra expenses
4: Three years
Can i point out that many modders are 3d artists, coders, texture guys and so on. A modder is someone who alters a game (and the alteration can be anything from a retexture to a total conversion that takes out nearly everything but the engine)
Look at Valve software- the only game that they have fully made is Half life. Counterstrike, team fortress, day of defeat, left 4 dead, portal, alien swarm, dota and any other game that they may have been associated with were originally mods!