Agree with most of the points already made, especially about engendering respect for the teachers and their classmates, and being keenly observant about children's individual personalities, strengths and weaknesses.
And as a Reception teacher, please spare a thought for the poor old parents! It can be really hard sending a child to school for the first time, especially if the child is shy or a bit 'young' for their school year.
I think it's important to get the parents on side so that they can talk positively about school with their child and help them work through any problems. Don't slam the door in their faces - encourage them to spend a bit of time in the classroom now and then.
And try and have a quick word once or twice a week, even if it's just to say something like 'your DC had a good day today, played really nicely', or 'they are doing well with overcoming problem x'. Otherwise it's just like sending your child off to spend the day with a bunch of strangers and it's hard to know how to respond to questions and reactions from the child about things that have happened at school.
I think some of the 'MN obsession with reading levels' is about the fact that going up a reading level is a RARE piece of solid feedback about how the child is actually doing. It seems nigh on impossible for a Reception age child to talk about their day - how they are feeling about school etc, so it's important for the school to communicate regularly with the parents on their behalf.