Ok, I try to break it down for you a bit.
Basically, what you want to reach with your crit factor is for it to be so high that Haymaker crits at a nearly 100% rate (without using the glyph for it). Beyond this point, crit is 30% less effective than getting the regarding stats in power.
The value to aim at is 331 crit (fully buffed). If you got a myst in your static, you don't need so much crit on your gear and if you have to decide for either a crit roll or a power roll on your necklace, you should check your crit stat first.
So, for your gear, try to reach 331 crit (if you are running with a mystic you want to go power ring + earring and crit necklace, ring and earring) and then roll everything else on power.
Normally, with good to perfect stats, you run with mixed jewelery, Quatrefoil Brooch (6/3), Belt (6/3), Necklace (4 Power), Double Energetic Etchings for Weapon and Gloves and Circlet (this is a nice item to switch stats on, either 8 crit or 4 power, depending on your crit value at this point).
Hope that brought a little bit of insight.
For your second question, power does NOT help to keep the rage. You should glyph rage generation on certain skills in your glyph setup which helps you to keep the rage. Otherwise, try to gain perfect blocks and chain your attacks well with attack animation cancelling.
Only stats which help to maintain a nice rage level are cooldown and in combination with that, attack speed.
If you got any more questions feel free to ask, I am going to try to explain as well as my english skills allow to 