No reason why you can't feed them. You want them to draw as much comb as quickly as possible if the other 6 frames are on foundation. They will use that feed to produce wax, not necessarily store for honey. They will need the extra boost until they can actually make more bees. Most keepers will tell you to feed them until they stop taking the feed.

As far as when can you open for inspection, I would wait at least 7 days from the time you brought them home. The guy I bought them from said wait 14 days so you don't endanger the new queen. Most people wait a week. It seems to be a good rule of thumb.

As far as spacing: Squeeze them together so all the frames are touching, then just center the 10 frames in the middle of the hive body. You want them to touch, or the bees will just build comb between so they do touch anyway, then you'll have a hard time getting them apart when you do inspections.

Where are you located? have you found a beekeeping association or club nearby? They are great places to find a mentor.

Here is a link that might be useful: Beemaster