I can't say that I've seen bikes with such parts in them being more prone to squeaks and other noises, nor can I speak for stiffness. This type of adapted setup isn't terribly common, and every one is a little different, so it's hard to be scientific.
For your crank, use Shimano Hollowtech II bearings or something specifically designed to be Shimano compatible. GXP is SRAM's standard- it's 24mm on the drive side, but smaller on the left. FSA's MegaExo bearing standard claims 24mm, but it likely won't play nicely either.
Below is copy/pasted from a post of mine from a couple weeks ago.
Here's some quick googling for relevant items for using Shimano cranks in newer frames. Shimano really isn't the BEST choice for BB30/PF30 frames since Shimano ONLY makes 24mm spindles. FSA, SRAM, Rotor, and many other manufacturers have 30mm spindle options on their cranks and provide their own native bearing sets as options.
Wheels Mfg PressFit 30 to Outboard Bottom Bracket for 24mm Cranks (Shimano) This is pretty typical- cheap and easy to install.
Wheels Manufacturing BB30-SHIM This is probably a better bet.
Adapters that allow for threaded bottom bracket cups also exist, but I think one of those methods above would be better.