Chapter 8, Page 93
As of level 20, HP totals are very high, averaging around 2,000. When we started playing they were around 10 to 20, but the CON scores kept getting higher and higher. I also decided about halfway through the game that most types of armor should also give HP bonuses based on how much protection they offered, in addition to armor class. (In the new system I'm working on for Mystic Revolution, there will be no armor class and all protection from armor will come in the form of extra HP.) So, the result of all this is that HP totals multiplied and eventually grew into the thousands.
We came up with a formula for figuring out one's HP which is as follows: Max HP = (HP BONUS x LEVEL) + (CON multiplier x LEVEL) If you do the math yourself, you'll see that Tetsuya's character has a base HP of 1,240. The other 1,700 HP comes from his armor, which is the highest armor total of anyone in the party. This makes sense as he is the tank and wears the heaviest armor. It's also why his Reflex Roll cap is lower than other characters'.
The Temporary HP section is primarily devoted to a utility spell which Heather has, called Earth Shell. It adds a fair amount of temporary HP which is increased by her Wisdom score. By the end of the campaign this spell would add 1,380 temporary HP.
AC works basically the exact same way as it does in DND 3.5. The enemy rolls a 20 sided dice, and if the total is higher than the player's AC, the attack is a hit. Towards the end of the game, a common enemy's attack bonus was usually around 40-45.
+All Rolls works just like it sounds. In order to keep the game balanced certain types of rolls had to be excluded from this, but it works for most kinds of typical 20 sided die rolls: attack rolls, saving rolls, and skill rolls. Also for "bonus damage" rolls that some characters have.
"Fortune" is a special ability (generally given by the feat "Lucky Charm") that allows you to reroll any roll once. The drawback is that if you roll a 1 while rerolling, you recieve the status "Bad Luck" and can no longer use fortune for the rest of the day.
Initiative works exactly how it does in 3.5 (at least I think so.) Everyone rolls initiative at the beginning of combat, and then the order of battle turns is decided by sorting the totals from highest to lowest.