There are a few things on my car that I have seen that I am not sure about and one of them is the retention of the steering wheel.

Firstly, I am replacing the M14 nyloc as it looks to be well used and not really locking any more, what is the correct torque on this?

Secondly, there is no washer behind the nut currently and it is just tight against the aluminium boss, should it have a washer as well?

45-55Nm for the nut though I've never actually torqued one... Just do them up tight.
They didn't have a washer under them.

No washers they just go tight on the tapered shaft.
My wheel boss said 31nm but I just did it up tight but not too tight as it's Ali.