Shane,if you don't want to waste a lot of money,don't buy broadheads yet.For that matter,forget any preconceived ideas of what broadhead weight you want.Until you bareshaft tune your setup,you will have no idea what point weight you will need.
1.I think you better leave the shafts 32".Your draw may be over 30" now,if not,it might expand later.
2.I think .400 spine arrows will end up too light with a point weight of 125,GT 55/75's would weigh app. 450 grs.
3..340 spine or GT 75/95's would work with a 100 gr adapter and app. 225 gr point.Black shafts would give you app. a 625 gr arrow and trads would give you app.655 gr.Either one would work great.
4.A good route to go would be get a dozen 75/95 GT blems from Big Jim,if they are available.Then figure out the tuning and once tuned,you will know your ideal point weight and can shop for broadheads.There will be plenty to choose from.
5.Forget spine charts.You have to bare shaft tune to get where you want to go.Go to bowmaker.net ans study the tuning info.
6.Since you will be using full length shafts and not cutting,tuning will be a simple matter of changing point weights till you get good flight.It doesn't get any easier.I would 75/95 shafts,100 gr inserts AND field points 200,225,250 and 300 grs.If you get arrows fletched,you need at least one bare shaft.I normally use 3.