This is kind of a confusing topic, keep things even but preference toward item level (provided it doesn’t reduce intellect). Favor crit a bit but keep the rest of the stats even.
Still sound about right?
Intellect is your biggest thing, as usual. Your secondaries depend on your hero spec though.
Flameshaper likes Crit and Haste in roughly equal measure followed by mastery then versatility.
Simming usually prefers haste with flameshaper. I think you want about 27% haste and 20% crit, plus ilv as mentioned.
Ironically if you’re playing PvP it’s the exact opposite, vets and mastery are your top secondary stats. But I’m assuming you’re looking for PvE advice so I’d follow the above advice 
Scale commander is crit mastery with a solid amount of haste. I try to keep it around twenty percent
This isn’t really true. The vast majority of high rated Devs in PVP are playing haste over mastery. You lose out on way too many necessary globals playing with such low haste in an environment that’s this fast paced.
Ultimately play what you want but I think people are having more success running haste>mastery for PVP.