Tax charges are separate and AFAIK they can't be mentioned in this trial... I did also hear that Geroge's prior convictions/arrests can't be mentioned either - so a history of swallowing drugs etc.. can't be brought up for example.
Yes, the police handbook does seem to have that technique in with a specific picture. I don't believe he was restricting his breathing as it would have taken much less time than 9 minutes - I reckon the sort of holds hurfdurf is super keen to demonstrate on people would have them tapping out or unconscious much sooner that than ergo rather moot other than as an illustration of them being a bad comparison here.
I'm open to the notion that perhaps during the process of holding him down there were periods where the knee made breathing difficult but then again, it's quite plausible that it was only pushing down a bit to hold him in position, we don't know that his full body weight was on the knee (very unlikely that it was). It certainly does seem to be an approved technique they're trained to use:
here is the picture from the Minneapolis Police training manual:
Note they mention sudden cardiac arrest as a risk there (and that is quite plausibly what happened here), they also note to call EMS to get them on scene - the officers did do that - they'd already called for paramedics early on re: the cut Floyd suffered during the faffing about trying to get him into a police vehicle initially but also placed a second call once they had to restrain to upgrade the urgency of the call.
and some comments from a thread detailing an earlier court motion by another officer (Lane):