? about butcher block counter top build.

Just my opinion:
1) yes, butt them together as tight as you can. And it’s an easy fix later on if a gap shows up.
2) I think it will look better with the edges exposed than the end grain method.. Probably easier to finish also.

-- "You can lead a politician to water, but you can't make him think." Kinky Friedman

Butt ends will not present any problems since wood doesn’t expand lengthwise. Looks are in the eye of the beholder so I can’t offer any input there other than to suggest that you look at cutting boards here on LJ. Personally, I love the look of end grain and it would give you the opportunity to introduce some very attractive design elements.
HTH

-- Art