My DD basically taught herself using the SM books for 1st thru 5th grade ones. We bought the textbooks, work books and the 4th/5th challenging questions. I specifically did this because I wanted her to do the drills. The SM drills are not at all onerous. She would sometimes ask questions but it was so infrequent that I cannot recall even one example now.
There was an adjustment to learning from the AoPS style text and I did work with her intensively for the first couple of weeks after which she seems to have adjusted and I am needed infrequently. Of course, I show interest and talk things through with her every so often because I do have no small amount of concern that she may be whistling along just skimming the surface, so to speak.
So far my fears have been unfounded and am very impressed with the AoPS discovery based approach and my DD's apparent absorption of the material so far. The only niggle that I have with AoPS is that all 'virtual classroom' sessions are held at hours convenient to West coast folks. If a student keeps up with the recommended reading and prep work, the classroom sessions, though enjoyed, are really just gravy.
Reading I really wouldn't worry about. My immediate reaction is to wonder what it even means for a 7yo to be 4 years ahead in reading. I know there's an argument for that being wrong, but I do still think there's a case for saying that once your kid can read and enjoys reading all future reading skills will take care of themselves, given plenty of material.
Maths: make sure there is challenge; the nominal grade matters hardly at all, it's all about hard problems.
^^^ I fully concur with the above.
IMO, once reading proficiency has been acquired a child is only limited by their natural curiosity, time for reading and access to materials that allow interests to be followed.
