I'll answer yours now.
1. I have the cash for Chapman, but I'm not getting him. Rumours of a niggling injury, and the fact that he is over 600k, keep me clear. I think he will drop in price, and if he gets to abuot 570 or so, I'll snap him up.
2. Hard to answer, because like you said, similar situation. If you already have the Chad, then downgrade Bowden and get B.Johnson. Otherwise, get Bowden I'd say.
3. I would suggest Armitage, though he isn't guarenteed to play round 1. It may come down to how he plays this week. People are suggesting that there are still big names to come back into the Saints midfield, but I'm pretty sure Hayes, Del Santo,Montagna, Ball and Harvey all played on the weekend, and Armo still got 144. I've rated this kid since I first saw him play in a Saints intra-club last year, and I think IF he plays, he will get the scores and rise we are looking for.
4. If Muston is out for the season, I'd say he will get promoted. However, it's unlikely that will happen in the first few weeks. Generally promotions happen after rookies have a chance to prove themselves.