To be honest Ryan is the ONLY actor that is capable of pulling off the Deadpool character. Yeah he wasn't the "best" Hal Jordan and I could probably name a few who were a much better choice to be Hal but oh well.
From what the director said, is that they want Deadpool to break the fourth wall as he does in the comics and the games, Reynolds had already signed on to the Deadpool movie before there was even a script written for him.
Also for the bullshit thing they called deadpool in the Wolverine origin's the director is just ignoring it all together, seeing as both Reynolds and the director said that wasn't Deadpool to any degree.