I've been a LEED AP for 5 years now and it's helped me. The LEED AP is mostly for marketing at this point. Marketing yourself to employers and marketing your company to customers. Customers seem to have this view that if you're not a LEED AP then you don't know anything about sustainability.
The main electrical component in LEED is lighting.
- One credit limits light pollution on the site.
- One credit is for daylighting inside the building.
- Beating ASHRAE 90.1 limits on connected lighting load.
- One credit for onsite power generation. (solar, wind, etc.)
- And low mercury lamps have been used as a bonus credit.
It's a little surprising there's not more electrical related items in LEED.
The LEED AP test covers the whole LEED system. With extra focus on the picky details of the credits. It helps having several years of experience designing buildings and working with other professions to understand the whole design process. The last test version had about a 35% pass rate. Rumor has it the new version will be more difficult. Paying for a several day training session seems to improve odds of passing but some of these programs are poor quality and are just chasing your money.
There's a forum here full of people studying for the test. Most of your questions have probably already been asked here. You'll just need to look around some.
http://www.areforum.org/forums/forumdisplay.php?f=47