Hi roverdude45,
It's a very interesting bunch of questions you bring up.
I had another resident in the street stop yesterday to congratulate me on the "now" best lawn in the street, honestly I get rather embarrassed by these comments as I know that the lawn is basically like a young child just entering primary school with much development to go before it leaves school.
If you look closely you can see the original mother plants by the light dotted bits. This is from constantly mowing it low and sending a message to the original sod to grow sideways instead of upwards. You are not really achieving much by filling in the low spots early in the period of the lawns development as we are trying to achieve the same thickness in the low spots.
This all takes time and there are no real short cuts. At the beginning of the next season I shall be doing a harsh cut back to the soil level and then doing a re-screeding of sand over the top of the whole lawn area and then applying fertiliser, then within 3 weeks I should have a totally even surface that will have a groomer reel used on it every second cut just to keep it thinner and not thatch up.
Currently I am cutting the lawn with my 14 inch SB 45 every two days.
Cheers,
BB