KJJ is saying the path to the PHP executable NOT the script, you have that.

Depending on your system it will most likely be something like

/usr/bin/php /Users/JLP/git_source/src/bin/walletnotify.php %s

if your on a linux-ish system (Mac, linux) you can run `whereis php` and that should tell you

Do whatever you would normally do to earn money, but ask to be paid in Bitcoin

I have a feeling these days faucets are going to take a verrrry long time.

Depends on the level of security you are looking for. The most secure option right now would probably be Armory but that would be a client on your local computer not a hosted/cloud solution.

Blockchain definitely has a decent amount of people using them, at the end of October the were around 500,000 wallets
ref: https://twitter.com/blockchain/status/395190582202470401

As far as specifics about security, this is a post from the Developer of Blockchain.info entitled "How secure is blockcahin.info"
http://bitcoin.stackexchange.com/questions/5249/how-secure-is-blockchain-info/5255#5255

The hashing itself is the confirmation of transactions that have taken place, so this important for the entire Bitcoin system.

To get people to do this work there needed to be a way to incentivize people, hence the "reward" for solving the block, which is the issuance of new coins to that person.

The reason it takes a lot of hardware now is because alot of people are trying to earn these rewards and the Bitcoin protocol self adjusted the difficulty of solving these blocks to keep it on average around 10 minutes between blocks.

So, if noone else started mining after 2 years ago then we would still be good with few kHash/sec