Could one with a 4.0 GPA from Howard University get into Harvard Law?

It's possible. Everything would have to go in your favor, and the likelihood of all those things happening is quite slim, but it's possible. I don't say that regarding Howard University, but about anyone trying to get into Harvard Law. It's difficult for anyone, from any school. Here's what you'll need: a flawless or near flawless GPA (3.8-4.0), a fantastic LSAT score (minimum 170), great letters of recommendation, and a well-written personal statement. There are books to help you in each of these areas, and each is as important as the others. Don't just assume good scores will follow (unless you've already obtained great scores); the LSAT is very difficult until you get the hang of the questions, and the personal statement is more difficult to write than you think.

They also look for volunteer work from various places Habitat for Humanity Soup kitchens Childrens hospitals....etc.

it depends on a lot of factors, kids with alumni parents always have first shot--regardless of their GPA. They will not care if you were in a sorority, and although the extra curriculars are good, they will look more at what volunteer service you have done. Every kid applying to Harvard has a perfect GPA and SAT score, so they usually rely very heavily on the volunteer work and usually pick those that have years of volunteer service to there credit, just have a few months to put on an application will not help you

Line up with the other 20,000 applicants with similar credentials. You have the same chance as any of them

A 4.0 is the highest mark possible right, at least the last time I looked it was, and a 4.0 from a college such as Howard should carry the same weight as a 4.0 from another, that is unless other issues prevent you from entry, and I hope it don't, good luck.

Well of course if all that happened you'd get into Harvard Law, but I'd doubt the plausibility of this combination, especially at Howard. Here's something to consider, too. While you can get a degree in whatever you want and go on to law school, it would be logical for you to get a degree in something such as business. Try to pick a major that could translate to an actual job after graduation, in case you decide not to go to law school or get accepted. A school is also not likely to allow you to take 3 concurrent majors, and you usually have to be a stellar performer to even make 2 work.

Yes, but just make sure you can afford it.