Hi rrbrigi:
Link to ORT reading levels by age here: www.oup.com/oxed/primary/oxfordreadingtree/chart/
Several things:
Class R is about settling children into the school environment and primarily this takes place through learning through play
In many schools Class R is quite relaxed about the academic (reading, writing, arithmetic) side of things, because they are working on the social skills (playing well with each other, following instructions, sharing, listening, etc...).
The first term is usually entirely about the children settling into this environment.
The second & third terms starts to focus on reading/ counting/ writing skills.
The pace is set by the teacher and depends on how she/ he wishes to handle the class. Some opt for as much whole class teaching as possible - others have a broad range of ability levels to deal with so divide the children into groups for reading, writing and maths.
Mumsnet info on Reception year here: www.mumsnet.com/learning/reception-year/the-reception-year
Children are continually assessed - but reading is also about speaking aloud, expression and pronounciation. So although your son may well be able to understand silently reading pink ORT band books - this may not be all the teacher is looking for.
In many ways Class R is a continuation of nursery Early Years Foundation Stage learning - and indeed your child will be assessed against this. Info here: www.foundationyears.org.uk/early-years-foundation-stage-2012/
From Year 1, children will move onto the national curriculum and the school day will become more formal. Year 1 and 2 will have 2 recess breaks + a lunch recess each day but from Year 3 (from entering Juniors) children have just one recess break a day.
It is good you are eager for your DS to get off to a good start - but he also needs time to settle in. But the most important thing you can do right now is support reading at home, with daily reading for 10 - 15 minutes or so, practice counting to 10, to 20 and to 100 as much as possible and start encouraging attempts at writing as much as possible. At this stage letter sounds, rather than letter names are o.k. - so 'ah' instead of A.
HTH