Reading and writing skills build in a fairly predictable sequence — this hub groups every language arts resource on the site by where it fits, so it's easy to find the right level for where a child actually is right now.
A child can decode fluently and still struggle with comprehension, or vice versa — both need direct attention rather than assuming one automatically follows from the other. See Helping a Struggling Reader for identifying which one needs the focus right now.
Roughly: letter recognition, then phonics, then blending into words, then fluency, then comprehension and independent reading. Writing and grammar build alongside reading.
No — phonics is decoding letters into sounds and words. Comprehension is understanding what those words mean. Both need direct attention.
See our guide on helping a struggling reader, which walks through identifying whether the struggle is decoding, fluency, or comprehension.