I've recently purchased some 7.5" x 9/16" engineered hardwood (oak) that I plan on installing this weekend (staple down). It's been sitting in the house acclimatizing for several days now. The application will be over a crawl space with a wood subfloor. The crawl space has poly down already. From talking with a few folks and reading as much as I could online, I've come to the understanding that I should probably install a vapor barrier on top of the wood subloor and should also consider an underlayment. Does anyone have any suggestions for a specific vapor barrier and underlayment?

Also the foundation wall is against the far side of the room, but this is also the shorter side (by about 3') due to some built in cabinets. Does it make sense to start at this shorter, outer wall, or at the longer which will result in a decent amount of traffic over the boards as they flooring is laid across the room?