Mikael said ALL of those instruments are real on the record. he said none of them on the record are done with a keyboard. watch the part 8 watershed video, he talks about it.
I haven't got the album yet, but I agree with Perdido; shouldn't the additional instruments/players be listed for each song they appeared in? Sort of like in the booklet for Scott Walker's Drift album? Of course, I guess not knowing adds a bit of mystery, but if I played oboe for opeth I would certainly want to be credited... not that I can play the oboe...