Brakes Sensor/Replace Q's?

[mcomet]

Hi,
I am starting to think about some DIY stuff for my box. I haven't yet done anything, don't yet own a jack or jack stands... I am planning on a front bumper removal and radiator washing this weekend. That will be my first semi realjob.

Anyhow knowing my front brakes are around 35% right now... I am considering doing a brake pad replace in the future ... My Q's are...

1. For the standard S brakes I have, how do I determine if rotors also need to be replaced? What is the thickness to check for?

2. I had new brake fluid and a flush done a few months ago by dealer... so I assume that is good.. Dealer told me maybe does that every year or two... How often do people here do it?

3. Biggest curiosity...dealer told me save $ and wait for the pad sensor light to turn on... which apparently triggers at around 15-20% aka 1.5-2mm It sounds like a lot of people change earlier.. when do people usually change pads?

4. bonus Q... any recs on a jack and jack stands? I don't want to break the bank...I am fine with something decent but safe... Just pick one up at a local auto store or such?

thanks,
comet