As long as your devotion to green and blue is less than seven, Kruphix isn't a creature.
You have no maximum hand size.
If you would lose unspent mana, that mana becomes colorless instead.
4/26/2014 As long as Kruphix is on the battlefield, unused mana will remain in your mana pool as steps and phases end (although it will become colorless). This means you can add mana to your mana pool and spend it during a future step, phase, or turn. Once Kruphix leaves the battlefield, you have until the end of the current step or phase to use the mana before it disappears.
4/26/2014 If unused mana in your mana pool has any restrictions or riders associated with it (for example, if it was produced by Cavern of Souls), those restrictions or riders will remain associated with that mana when it becomes colorless.
4/26/2014 The type-changing ability that can make the God not be a creature functions only on the battlefield. It’s always a creature card in other zones, regardless of your devotion to its color.
4/26/2014 If a God enters the battlefield, your devotion to its color (including the mana symbols in the mana cost of the God itself) will determine if a creature entered the battlefield or not, for abilities that trigger whenever a creature enters the battlefield.
4/26/2014 If a God stops being a creature, it loses the type creature and all creature subtypes. It continues to be a legendary enchantment.
4/26/2014 The abilities of Gods function as long as they’re on the battlefield, regardless of whether they’re creatures.
4/26/2014 If a God is attacking or blocking and it stops being a creature, it will be removed from combat.
4/26/2014 If a God is dealt damage, then stops being a creature, then becomes a creature again later in the same turn, the damage will still be marked on it. This is also true for any effects that were affecting the God when it was originally a creature. (Note that in most cases, the damage marked on the God won’t matter because it has indestructible.)
4/26/2014 Your devotion to two colors is equal to the number of mana symbols that are the first color, the second color, or both colors among the mana costs of permanents you control. Specifically, a hybrid mana symbol counts only once toward your devotion to its two colors. For example, if the only nonland permanents you control are Pharika, God of Affliction and Golgari Guildmage (whose mana cost is ), your devotion to black and green is four.
4/26/2014 Numeric mana symbols (, , and so on) in mana costs of permanents you control don’t count toward your devotion to any color.
4/26/2014 Mana symbols in the text boxes of permanents you control don’t count toward your devotion to any color.
4/26/2014 Hybrid mana symbols, monocolored hybrid mana symbols, and Phyrexian mana symbols do count toward your devotion to their color(s).