under the space for "How long do you intend to stay in the U.S." in form DS-156, for guys applying for H-1b visa, should the duration be written as 1 year?

Also, guys who have a B-1 multiple entry visa , while filling up DS-156 for H-1b, under the heading " Have you ever been in the US?" , under "when and how long?", are we supposed to mention all the trips to the U.S. and their duration or only the latest one?

Thanx guys.