Fee and Application Question

[mechew]

Can someone please explain why the Bitcoin-QT app for OS X asks you to enter your pass phrase before it warns you about exceeding your balance because of fees?

Also why does it tell me there's different fees?  First it was .00000001, I adjusted and was then informed its .0001, now a couple days later its .0002?

What happened to no fees?  I thought I could do one for free as long as it was no rush?

Also note I'm trying to send .00670248 so its somewhat important since .0002 is just under 3%!

[DeathAndTaxes]

The min fee is per KB and only on low priority txns.   So more quick txns made with spammy inputs means larger more expensive.  If you are willing to wait for your coins to be old enough AND wait for a miner to pick the txn up for free you can send without fees. 

[BunsenBurner]

The fee depends on the tx size in KB, and you can estimate the tx size using the following formula.

http://bitcoin.stackexchange.com/questions/1195/how-to-calculate-transaction-size-before-sending

So if your transaction has 'in' inputs and 'out' outputs, the transaction size, in bytes will be:
in*180 + out*34 + 10 plus or minus 'in'

To send your tx without fee, your tx need to satisfy a few conditions.

https://en.bitcoin.it/wiki/Transaction_fees

A transaction may be safely sent without fees if these conditions are met:
 It is smaller than 1,000 bytes.
 All outputs are 0.01 BTC or larger.
 Its priority is large enough