I'd second the recommendation of N160 or N555, despite the latter being the 5 series it has similar energy content to the 1 series powders in the same burning rate range so should be kinder to the barrel that N550 or N560 which can be very erosive, especially if you run high pressures. N160 is quite bulky, I haven't seen the kernel size of N555 but when I did a search on google I got directed to a Vit page which listed it quite small, similar to N550 so it should pack well in the case.

I would only use small primer brass if the firing pin is a good fit to the bolt face, I've read Bergara's can be on the sloppy side which can cause cratering and blanking, not something you really want to deal with. Large primer brass is more forgiving in this area although it won't hold up as well to stout loads, but Lapua is the brand to buy. There would not be that much difference between large and small primer velocity, there are many more factors that would affect velocity than the size of the primer, make of primer being one example.

The only other thing to watch is the throat length vs magazine length unless you're happy to load singly. Many of the heavier bullets in 6.5mm especially the Hornady are very long and can intrude into the case limiting powder capacity which with a 22" barrel you would want to maximise.

As to dies I use/d a combination of Whidden, Redding and Forster, Wilson are also very good but not sure if they do 6.5 Creedmoor.