I have a few questions.
Actually you have many questions. They are good questions, but it takes time to answer questions, so next time please pick your top five or less. Because you asked too many questions, I will not answer all of them.
How did you get the idea to do this?
I've been looking for a way for open source developers to get real money for a long time. I know about charity, advertising, consulting; but I also know that for most projects, even those that have several thousand users, all of those sources of income combined give less than ten dollars a month. For instance the bitcoin charity pools:
http://forum.bitcoin.org/index.php?topic=20455.0currently have only a few GHash between them, one percent of that divided among all the bitcoin developers is less than five dollars per developer per month.
I don't know how successful groupcoin will eventually be, but I do know that the current methods of paying for open source development are nowhere near enough.
Did you get the idea yourself..
Yup.
How did you come up with the 50% percentage?
For maximum protection against thieves, the percentage should be 0%. For maximum developer revenue the percentage should be 100%. I chose the middle as the best tradeoff.
Why did you only include bitcoin open source developers, if you specified "general" open source developers?
It will start with only bitcoin open source developers. If it is sufficiently successful, which I define as being very roughly more than 100$ worth of groupcoins per developer per month, then the criteria would be widened to open source developers in general, not just bitcoin developers.
Why do you think this idea will be successful, when so many have failed?
To the best of my knowledge, no one has attempted to make a whitelist coin to pay open source developers, so none have failed, because none have been tried.
What is your ideal ratio of bitcoin:groupcoin miners?
Eventually, I think people should have roughly equal amounts of bitcoins and groupcoins or derived coins for maximum diversification. Mining ratios would derive from that.
Why would you "incorporate code that would keep the whitelist updated from the web every two weeks", but not incorporate code that would automatically donate 50% of the 50 BTC bounty to the group of open source developers? Do you think that if miners mine every 10 minutes on average, hundreds and potentially thousands of small transactions will generate unnnecessary work for the network? Wouldn't it be maybe more efficient to create a central site/location where miners would donate the 50% as a single transaction and then the site would store the balances of the developers, which they could then somehow access and transfer when they want (or maybe once daily, or at least 0.1btc, etc.)?
If groupcoin works, I plan on offering groupcoin bounties for a more sophisticated derived coin. I'm starting with the simpler groupcoin because going directly to the sophisticated coin might be a bridge too far.
Do you plan on keeping the currency as BTC? 1 Groupcoin BTC = 1 Bitcoin BTC? How will that work, anyway? I don't think a Groupcoin BTC will be able to be sent to the Bitcoin network since this is a separate blockchain, right?
Groupcoin is a separate blockchain. Not only is the genesis block & port different, but also the rules. Any value relation between bitcoin and groupcoin would be determined by the market.
If setting a single master groupcoin/bitcoin address (see the confusion?) is a potential security risk, there could be a master list of addresses which would rotate on every new block found, or every few dozen blocks, or a similar criterion. They could be fetched from a trusted location.
This project seems to be rather centralized, with lots of trusted individuals, as opposed to the main Bitcoin project.
No matter how you try to work it, because you need a synchronized whitelist, there will be centralization and there will be an additional security risk. However, this is the only way you could direct 50% of the mining revenue towards developers, or some kind of good cause, rather than the current roughly 1% charity; so the tradeoff is worth it.