Bullet weight and bullet composition (lead, jacketed, plated) are what matter, not manufacturer. Components are never interchangeable in a load recipe. When you change any component you must back the load down to a safe starting load and work it back up.
Yes indeedy - granted you may end up close to the powder charge you were originally using, but the steps for working up from the starting load must be repeated every time a component is switched.
As others have said, look into a reloading manual - if you cannot afford one, check your local library. I have made it a point to buy several manuals for the one I work at.
As to primers, I use a Lee hand tool - to me it is faster as I do everything in stages and additionally, as I am applying the force to seat it by hand rather than vast amounts of leverage via a large handle I can get a better feel for something being "off"