Yes, there are boxers without elastic waistbands they are called French Fly Boxers. They are usually fitted and have a 2 to 3 button hole.

Yes there are mens pants with elastic waistbands. JcPenny, Kmart, and Target are a few places that sell them. The ones at JcPenny are called : Men's Towncraft Plain Front Full Elastic Pants

Most maternity jeans offer drawstring waists, but some use elastic waistbands.

well you can buy them at a ross the most i have seen them were $10 or maybe lower

Yes, however it depends on the specific country or community cultures and traditions,