2
If I create two transactions:
Would nodes propegate these two transactions? Would miners mine them?
In other words, if transaction T2 depends on T1 and I want to broadcast both together - can I save some fees on T1?
1
Probably not. Clients can set whatever rule they like for transaction fees, but they normally adhere to the Satoshi client rules described at https://en.bitcoin.it/wiki/Transaction_fees. However, note the section on transaction priority; if you have an address holding some old coins, it's quite likely a transaction out of that address will have high enough priority for you to avoid transaction fees by default.
To implement what you describe, you would need a client that does something like hold all low-fee transactions in a small pool and watches for new transactions out of their output addresses. That's certainly possible to implement, but it seems to me that it would be the sort of service you'd pay a premium for, not receive a discount on.
FYI another user just told me he tested it and it does work ... I guess testing this is the best way to understand whether it works or not, rather than relying on theory. – ripper234 – 2014-03-13T12:15:30.410
1Maybe a lucky connection to a pool like Eligius that accepts no-fee transactions? I agree, testing is the way to go. Too many variables. – Nathan Cook – 2014-03-13T12:45:33.050