Brake Pedal 'Squeak', Brake Fluid Replacement....Ideas?

[FlaAveo5]

2nd and 3rd Question for today. Ok..my brake pedal has been making a mild 'squeak' upon pressing for like 6 months. Not getting worse. Sounds like 2 pieces of metal that need a drop of grease shut up. Only makes it when pressing,not upon releasing of the pedal. Any ideas on where to shoot some lithium grease on the pedal arm?? OR is it something more dangerous?? OR a common thing in older cars/Aveos?? Its just annoying.

3rd: Ok. Got to replace the brake fluid totally. Can take it to a 'mechanic' for $80 locally, good deal?? Or getting screwed? Can I use DOT 4 or 5??? Or is 3 the only one?