B0157 the main thing to check is to verify the operation of the VCT solenoid. You're looking for a sticking or stuck VCt solenoid valve caused by contamination. Refer to vehicle specific repair manual to perform component tests for the VCT unit.
The B0157 check engine lamp is perhaps the most troubling of lights because it could mean so many different things, from you didn't screw the gas cap on tightly enough to look out for pistons flying through the hood and into the stratosphere. The easiest way to find out what this light is telling you is to hook your vehicle up to a scan tool. OBD 2 diagnostic tool looks a little like an oversized calculator and plugs into a communication port inside the car. After you instruct it to perform the scan, it speaks with your car's computers to find out exactly what's prompting the light to turn on.
The leak detection pump is part of the evaporative emissions system. This system tests the fuel system to make sure it is not leaking fuel vapors into the air. The system pulls a vacuum on the fuel system and holds it for a period of time.
Indicator and headlight bulbs need regular maintenance for them to keep functioning properly. Also the car paint ought to be in good condition because that reduces the chances of rust taking over the body of your car. This is one of those car maintenance problems, which are easy to handle, given the variety and quality of products available in the market today.