(With the exception of 3, they don't seem unreasonable to me.)
I thought I would see "Students should be able to solve problems in more than one way," but I didn't find that particular phrase on the page I linked to. Do you know where it comes from?
There's nothing wrong with having students persevere in solving problems, but this has been interpreted as "struggle is good", and giving students problems without much help or guidance and having them "struggle" so that they can learn. There are ways to do this productively, of course. But the "struggle is good" philosophy is one that's been around for a while, and the SMP's are gasoline on the fire of bad math practices that have been around for 20+_years.
However, MCPS defines accelerated tracks on their web site. Acceleration opportunities start in grade 4, and in one option, this leads to algebra I in grade 7. Considering that CCSS, at most, expects only pseudo-algebra II content, it's not clear how they prepare these kids for algebra in 7th grade. (They don't.)Whatever they do has to be something not based on anything to do with CCSS. They can use their fuzzy UCARE words, but something else has to happen.
They start compacting the material in fourth grade, but the acceleration is based on the same fuzzy content and ideas of K-6 curricula. The only real change is when they get to a real algebra textbook that is far above what CCSS expects. Instead of a proper pre-algebra course, they force kids to suffer through "Investigations in Math." In other words, the only kids who will be on a STEM track are those who get math help at home or with tutors.
K-6 math ignorance has not been fixed by CCSS. It is just hidden by acronyms like UCARE. MCPS can make a connection to Calc AP as a junior in high school, but the onus is completely on the students and parents to make the nonlinear transition from K-6 fluff math to the real math textbook high school sequence.
CCSS is a one-size-fits-all (algebra II) expectation and anything above that is left up to the students and parents. MCPS can define the paths and students can make it onto those paths, but educators don't (want to) know how kids get on those paths.
I went through this exact process with my son. I worked with him on the (stupid) 6th grade Everyday Math material in the summer before 6th grade so that he could take pre-algebra in 6th grade. I know exactly what that nonlinear transition is all about. CCSS fails in that it does not address the transition from the fluff ideas of K-6 to the real world STEM options of the calculus track in high school. When I was in school, I got to calculus with absolutely no help from my parents. This is impossible to do now.