Well how about that. I'd say that pretty much confirms Fring left the note. It's an acrostic, I believe.
I'm still not ready to write Chuck off as all bad, but he's pretty bad here. He seems to take it really hard that people just don't like him the way they do Jimmy, apparently including their mother. And the fact that Jimmy can use that natural advantage in unethical ways is just too much for Chuck.
Almost everything shown about Jimmy makes it look like he's a good-hearted guy. But I'm not yet sure that Jimmy's ability to con people doesn't extent to the audience.
He's definitely sleazy, but he's never really been portrayed as a bad guy. Either in this show or Breaking Bad. He does bad (mostly unethical) things and he's not above hiring or at least facilitating the hiring of assassins (especially if they only focus on bad people; in fact, has he ever condoned harming innocents?), but I can't recall a single example of him being a genuinely vile person. Certainly not to the level Chuck is. I mean, not only did he not tell Jimmy about his mother's last words, but he didn't even have the nurse use the intercom to call him back even though he was still in the hospital.
I mean, the way he reacted to Chuck collapsing at the copy shop really says it all. He didn't care about himself, his career, or anything other than saving his brother. That wasn't him conning anyone, even the audience.