I can do a short run down of your questions.
I) No offer will be required as he's out of contract, not getting a game for GC and will almost certainly be delisted. Should we pick him up when they do that, absolutely. At most he's a worthless late round pick that GC will only use to acumulate points to match their 3 top 10 academy draftees.
II) Martin is contracted and not available. My understanding is he has no real interest in coming back to Perth.
III) Naughton would cost far more than we have and isn't worth it. So no.
IV) Sean Darcy is contracted, loves the club and is our reigning best and fairest. He's going no where and talk of trading him is silly. McDonald has a contract with Sydney and is likely to stay there for a while now Buddy's left.
V) Darcy for English is stupid for so many reasons. Darcy kills him each time they play and if English were to miraculously find his way to Freo, he'd come into the side at the expense of Jackson as the mobile 2nd ruck. Basically it's never gonna happen so don't bother.
The only real movement news is likely to be Henry on the way out and trying to get as high a pick in return for him. I don't see any likely young West Aussies looking to come home that would add anything to our side so finding a way to turn Henry and the rest of our picks into a package deal to nab some of Gold Coasts early selections is probably the ideal solution. Use the GC pick to grab Curtin. It's a pipe dream though.