Thanks!
But I'm not sure I get this... I've read about transaction fees on the wikiw:
https://en.bitcoin.it/wiki/Transaction_fees and I understand that there is a mandatory fee on very small amounts,
less than 0.01. But even if this has changed, the error message I get tells me that the amount I'm trying to send, 0.01 BTC, is
over the size limit. What size limit? Does this refer to the "blocksize"? The wiki says "0.01 BTC fee per kilobyte of transaction, but: If the blocksize (size of all transactions currently waiting to be included in a block) is less than 27 kB, transactions are free." Have I come above 27 kB? How do I know the blocksize?
Are other people able to send 0.01 BTC without paying fees?
Yes, the message you're seeing is a bit confusing. As you read, TXN with parts less than 0.01 have a mandatory fee however the client enforces a fee in another case: When the transaction has very low priority (and may takes weeks to get processed).
The priority of the transaction is computed based on txn_value * age_of_coins / tx_size_in_bytes. The age is how long they've been sitting in your wallet. If the
priority is low enough that the rest of the network would handle your txn very slowly the client (though only version .21) will make you put a 0.01 fee on it, which fixes the priority.
Normally, once you have a reasonably sized wallet with some reasonable aged coins, you'll not run into this issue. An upcoming version of the client reduces that fee to 0.0005, since 0.01 was getting a bit stupidly large.
The reason for this system is to prevent a transaction denial of service attack— without it I could simply bounce 0.01 bitcoin between two wallets 1000 times per minute and clog up the whole system just to be a jerk.
Regarding confirmation time, getting 6 confirmations in 11 minutes is unusually fast. The designed-in average rate of confirmations is 1 per 10 minutes.