You can go to any hair product place or even at your grocery store and buy a hilighter kit that comes with a hair cap. Using the hair cap that has small holes all over it and a pick that is included in the kit you can get the all over hair hilights that you desire.
Yes. Generally, any time you are highlighting/coloring your hair you want someone to help you for tough spots in the back. However, there is a cap that you can buy that has holes all over, you just pull your hair through holes, apply color. Buy at any hair store.
Yes, L'oreal has a kit that can be purchased at Walmart. The kit contains a cap that you pull the hair strands through, a hook to pull the strands through bleach and activator. Before putting on cap lighly brush all hair to the back put the cap on snug and pull the strands through the premade holes.
Many companies make such products. I recommend anything from Clairol. Their products are of high quality and affordable. You could also mix 1/2 cup lemon juice, 1/2 water, and 2 tablespoons vodka in a spray container and spray the mixture onto your hair. After an hour or two in the sun, you will have beautiful all-over highlights.
You could foil the strands you want to highlight, put the product on, and wrap it up in the aluminum foil (so it doesn't touch your other hair) or they also have caps you can purchase where you pull the hair through the cap and then color that hair.
Clariol makes a highlight kit complete with cap and instructions. You can find this product at a Sally's beauty supply, or any other professional beauty supply company that also sells to the public.