Quote from: darkfur93 on February 23, 2016, 06:21:25 PM

Today I been testing out Core 0.12.0.
I'm trying to get a better understanding how RBF works. Can you confirm or deny the knowledge I have on it at this time?

You should move this thread to a more advanced section, to get the proper answers you seek.
In the meantime, I'll answer only what is my understanding.

Quote from: darkfur93 on February 23, 2016, 06:21:25 PM

Any time a supported opt-in RBF transaction is broadcast over the network there will be a extra flag.
Could a merchant service see the flag and choose not to allow a 0-conf?

It is not "flagged", I believe the transaction will be seen as a "non-standard" tx.
Merchant services will be able, in time, to implement something that will recognize it and allow the
business to decide what they wish to do in real time. Like a warning pop-up or the like.

A merchant can not "choose not to allow" a 0 conf RBF tx, because it could within seconds, be a 1 conf tx.
In that event, the RBF issue is resolved and non-existent.
Merchants should tell their clients/users to wait for 1 conf, if that client/user chooses to use Opt-In-RBF.
Merchants should advise their clients/users on their payment page that they do not "honor" 0-conf RBF txs.

In theory, many things can be implemented that can assist the merchants with RBF txs.
Merchants should contact their payment processors and request that they provide such feature.

Quote from: darkfur93 on February 23, 2016, 06:21:25 PM

RBF allows you to change the receiving addresses. What about the sending address and amount?

The RBF feature only applies to the same outputs being sent a second time, to the same or another address.

If you performed another tx with a separate address which has different outputs from your original RBF tx,
it would be two different output txs, and would not effect you original RBF tx.

Quote from: darkfur93 on February 23, 2016, 06:21:25 PM

A larger fee is required to send a RBF transaction. Is there a minimum required higher fee or would a 0.00001 increase work?

I don't know what is programmed in 0.12.0 for sure,
but my understanding is any increase would cause the miner to pick up that new tx, over the first tx.

In theory, you would increase your fee so that it would be picked up in the next found block.
If your bumped up fee is just a few satoshis or etc, you will probably continue to wait with your second tx, as well.
Opt-In-RBF is really intended to "bump" your way to the head of the line during congestion or spam attacks.