How great is the effect of trees on noise pollution

The budget allows you to increase or decrease the effectiveness of your services at rip-off prices. Decreasing your budget by 50% will actually decrease the output by 75%, and increasing your budget by 50% only increases your output by 25%.

For power and water, I see no reason to increase the budget past 100%, it's simply easier and cheaper to build new buildings.

For services such as school or fire, I like to crank those up to 150% once money becomes no issue. This is because their effectiveness goes up while reducing how many of those buildings I need to cram into each area.

This probably isn't the case for you (and isn't for me), but it wouldn't surprise me if people with red/green colour blindness couldn't distinguish the colour used for residential zones from the colour for industrial zones, and those with blue/yellow colour blindness having difficulty distinguishing commercial zones from residential zones. Unfortunately, there doesn't seem to be any options for colour blind people, but one thing you can try is forcing the colour palette to one of the climates (Temperate, Boreal, or Tropical) in the options.