Re-siding 70 year old house?

Once the rain clouds go away (I am in WA so who knows when) I am going to start re-siding my house that was built in the early 1940's with fiber cement lap siding. My plan was to remove the cedar shingle siding and put tyvek over the ship lap exterior boards. But then I got to reading on the web and I am getting conflicting info. Some websites are telling me tevek is a terrible idea for ship lap, other web sites are telling me its great stuff. The main item I am coming across is that tyvek will allow to much air to come though walls, which may be true?

Can anyone put some reasoning behind which should be used in this case, building paper or tyvek?

Also while I am asking, behind a deck ledger what material would be best as well? We have a porch coming off the front of the house that I will be replacing at the same time.

Thanks in advance!