My bike stays in the smallest ring in the front for the vast majority of my rides. The cassette I switch all the time but like to keep it at 3 to get up the hill in front of my home. Then the road flattens and I switch to 4 and 5 and 6. I rarely use 7. As the hill start up I head back in the cog and reserve 1 for nasty hills and 2 for hills. I like a little bit of resistance to keep my cadence smooth but with no mashing.
Recently I've used the middle ring. I find it much faster but that it's harder to start up on hills except on the second easiest cassette gear (2) but not easy enough for quicker starts at street lights and stop signs.
I'm a big fan of coasting down hill. I very rarely pedal down a hill, gravity is nice help. It also lets me keep the bike at an easy to restart gear when I next have to stop at lights.
Definitely change into an easier gear before stopping! I read that advice in a magazine and immediately began doing that on my rides. I've watched other riders veer into traffic because they were in a harder gear and they leaned into the handlebars to mash the pedals but typically leaned into the lane with a car in it.