I just re-downloaded the two scenery and sound files in question and noticed that there are a couple of things just a bit different in both of the areas.
Brads BBQ files:
brads_skeena_river.zip contains the scenery files and unfortunately there is an extra folder included. It is named
notes and should be deleted before you copy the main Brads Skeena River folder to your FSX.
Besides that the two .bgl files for sounds, 1) music and 2) sounds are already in the scenery sub-folder of the Brads Skeena River scenery no need to copy them from the BradsBBQ_FSX.zip folder. This is why you hear birds without installing the sounds.
For Iggy's Harbor sounds the download contains two separate .zip file within the download. You have to unzip the
iggysharborsoundsandtrafficfiles.zip then uzip the first included zip file,
IggysHarbor_Sound_FSX.zip and install it according to instructions. After that unzip the second included zip file,
trafficIggysHarbor.zip and install that according to its read me file.
I will alert Doug about the extra folder in the Brads Skeena River.zip.
I hope all this makes sense and will help you sort your problems out.