Most car that use a lever with cable to pull brake will engage the rear brake pads (left and right). However, there are cars that will engage all four tires through certain mechanism. So, when the brake pad becomes thinner, the lever will end up higher for good grip.

Changing brake pads are not difficult job. You can opt for all pads change when flushing brake fluid. At initial stage, you can see the brake fluid is at Hi position. When brake pads wear out, the brake fluid level will drop down. When the level hits Lo, then you know it is time to change brake pad. This can be your indicator but don't let workshop top up the fluid in between brake pads change just because they want to charge you

For the air-cond not cold, you should ask if the refrigerant was low when checked initially. Then they can top up. If low again after even a year, if not months, then most likely the cooling coil inside car (called evaporator coil) got leak due to corrosion over time.

If the pressure said to be high on the high side, it can be due to many reasons. This can happen due to too much refrigerant filled in but in your case it should not because it was just filled buy the workshop. It could be blocked condenser or malfunctioned expansion valve. These can be cause by dirt in cooling system. Compressor is like car engine too. Compressor piston wears and metal dust could blocked the expansion valve. It can be cause by bad compressor but I would out it as last possibility because it cost more to change