The IMR-7828 is a good powder , I have never used the R-22 in that round but it may be a little fast for the 200gr pills since its burn rate is close to 4350.
The weatherby brass is gonna be the best as far as accuracy goes but for a bone factory gun I woulden't waste the money and its pretty soft so it doesn't last long.
As for reloading it I personaly like to use a FL sizing die and set it to just bump the shoulder that way it doesn't get to bad of a bulge above the belt. The Weatherby chamberes are desgined to have freebore so you most likly won't be able to seat the bullets out far enough to touch the lands and still feed from the mag , but if you can you MUST back off the charge a bit or your gonna get pressure spikes.
The Vanguard/Howa rilfes are good guns and make a great base to build a custom later , if you rig doesn't shoot up to par try having it bedded , the trigger worked and the crown recut. Another option that I did on a buddies 300Wby was cut the barrel back a bit (1/2") and rechamber it for 300Ackley without the freebore , makes for a more accurate and reloader friendly gun