Help me please to understand Steem Stats presented at steemd.com

I am trying to figure out the meaning behind the values presented on steemd. I summarized what I understood so far. I hope someone can help me to complete/correct the picture.

GLOBAL STATS

steem_per_mvests - this is Steem per 1M Vests.
-> Vests of an account in Mil. = Account's Steem Power / steem_per_mvests

virtual_supply - ???

current_supply - available Steem (unbound Steem + Steem Power?)

current_sbd_supply - total number of Steem based Dollars

total_vesting_fund_steem - Amount of Steem bound as Steem Power (Vesting Shares). For every 1 Steem created per block 9 Steem is added to this pool(?)

total_vesting_shares - total number of vesting shares. Corresponds to Steem Power.
-> Account's Steem Power = Account's vesting / total_vesting_shared * total_vesting_fund_steem

total_reward_fund_steem - Steem available in the reward pool

total_reward_shares2 - number of shares in the pool
e.g. "809037714622419596626201752532" (why this is such a large number??)

total_activity_fund_steem - ???

total_activity_fund_shares - ???

sbd_interest_rate - ???
e.g. 1,000, I was expecting to see this corresponding to 10% somehow

current_aslot - ???

recent_slots_filled - ???

participation_count - ???

participation_rate - ???

account_creation_fee - minimum fee required to create an account
e.g.: 3.000 STEEM

registered_accounts - number of registred accounts
e.g.: 78,099