It depends on how handy you are with the spanners. A running light is best sourced from a breakers.. there will be a few out there in good condition. Most lamps these days don't have a separate lens and "glass".. so you'll have to change the whole lamp.
The passenger door is a bit fiddly to replace, but again, if you can find the parts then fitting a new one is only light labour.. though that doesn't mean it's easy.
The light (if it's a melted bulb holder) can probably be fixed most easily by an auto-electrican. I don't know why you would change the loom... the sparks guys have wires and most of the connectors, so they'll be able to patch it.
Ralf S