My dd is also 6 and in "first grade" right now. She is easily reading the 2nd grade level Pathway Readers.
If your dd is reading at a 3rd grade level, I don't think it's necessary to have formal reading lessons anymore. I would have her read out loud to you regularly, however, and you can address any "gaps" in her knowledge on an as-needed basis. This is what I do with my dd.
For spelling, it depends on what you want to accomplish and what you think your dd needs. I am using All About Spelling with my dd now. It isn't very CM, but I happen to prefer a little more direct instruction in this area (one small area where I depart from a pure CM approach.) My dd was wanting to write more (letters to grandma, lists, etc) and constantly asking how to spell this or that so I felt like it was a good time to start giving her the "tools" needed to do this for herself. We had also not used a strict phonics approach to reading and so I wanted to reinforce this. I have seen an increase in confidence in both spelling and reading since we started this program, so it's working well for us. We also do copywork, so she is getting 'pictures in her mind of good spelling' ala CM as well. My plan is to continue with AAS until 4th grade and then switch over to a CM-style Dictation approach. (Obviously we'll re-evaluate that as we go along depending on what her continuing needs are.) I don't think it is recommended to try dictation before age 9 even with a strong reader, just because it is so many skills that need to come together (spelling, writing, remembering, etc.). If you don't think she needs a direct approach to spelling right now, then you can just stick with copywork until then.
As far as time goes....we spend about 1-1/2 on "formal" learning on any given day. This includes poetry, calendar, Aesop, history, math, cursive, spelling, copywork (daily) and one of these: art, character development, nature study, and geography. This does NOT include chores Bible, literature, reading practice, or French as these items are spread out throughout the day and continue even when we are taking a "break" from school. They are such a part of our daily routine we don't really think of them as "school" even though really they are.