Can you do a Sage Advice on dual wielding Hand Crossbows?

Can you do a Sage Advice on dual wielding Hand Crossbows? (ps if you say we can use ’em like automatic pistols, I quit. ;))

http://dnd.wizards.com/articles/features/sageadvice_feats

Net attack on a Hunter’s Mark target with the sharpshooter feat could deal 1d6+10 dmg?

Don’t spell saves seem a bit low?

Why is concentration based off of a physical stat and not a mental one?