Re: 30-338 needs some help to get started
Wouldn't worry too much about the brass, since it's plenty easy to come by. You can form 30-338 brass from either the 338 Win Mag (necking it down) or from 7mm Rem Mag (necking it up). Either way, brass shold be readily available to reform. As to the old ammo, this can occasionally develop season cracking, depending on how much the brass (particularly the necks) were worked in their previous loadings. Not uncommon for ammo of this age to start showing cracked necks, just from having been loaded so long. Take a look, and if there's no apparent problems, go ahead and fire them.
Lots of options as to scopes, mounting systems, rails, etc., so that one's on you. Take a look at Graf's, Sinclair, Midway, whoever, and you'll find more options that you can shake a cleaning rod at. Leupold's always good and not terribly expensive, and then there's NightForce. US Optics, etc., which can get pretty pricey.
The 30-338's a good cartridge, and has a bit better inherent accuracy than 300 Win Mag. There's a good bit of data available for it in some older manuals, and loads for the 308 Norma Mag should be virtually interchangeable, since it's essentially the same cartridge. Hope that helps!