Hello welcome,
Wind noise is a problem which blights all subarus, the pillar less glass is the reason for it, foresters tend to have problems with the rubber triangle on the front windows, there are diy fixes available in youtbue and there may be one in the how two guide on here,
Knocking is normally down to the rubbish plastic droplinks, ive changed the shocks and tops but still get the knocking sound, will be changing the links soon to metal ones hopefully this will cure it.
As for the oil issue I'm not sure is it a 2.5L engine ? Does seem odd to be going through that amount