Energy Sharing
I know Energy is shared between three Knights on the same account (like on one Steam account), but does it also apply to Knights of two different accounts (for example, an account here and an account on Steam) using the same computer?

If Kesk means CE is not shared between two accounts then he's right. Mist energy, however, is shared between any and all non-paid accounts on the same computer, no matter Steam, Facebook or regular account.
If you have bought energy with $$$ at any time with an account, it gains its own exclusive mist tank and becomes immune to mist sharing. The cheapest is $2.45
Does anyone know if receiving a Party Pack gift from a friend counts as making that account have its own ME pool? Or only the acct that actually bought it?

Receiving a party pack gift doesn't make the account a paid account.
Source: (with admin reply)
http://forums.spiralknights.com/en/node/11233
http://wiki.spiralknights.com/Energy_faq
im pretty sure if its the same computer it will default to the lowest amount of energy on the account if its free