When should I Fortify / Consume a hero?

Quite new to this (level in early 30s / 2 legendary heroes) and just wondering when I should consume a hero vs when should I fortify one.

Here is my guess. Could someone please correct me if I am wrong:

Consume: - Anything lower than a rare - Ideally same color (On this note, if my hero is, say, red/blue does it count them as ALL red and ALL blue for advantages and disadvantages or are any advantages/disadvantages diminished - ie half as good?) - Even better if they have experience (is it worth getting them experience first or am I better just getting my squad experience)

Fortify: - Only decent rarity - Always share a color - Good if they are "common" eg wisps so you can tier them up - Experience doesn't matter(?)

Any other tips?

At this point in time I have just removed an experienced (level 15ish) epic from my team and I am wondering if I should fortify a character with him or consume him...

TIA