#1 Is a line of sight required from the subwoofer to the soundbar as the description says?
This pertains to the maximum distance the wireless connection is rated to work at. Since most rooms in an average home are in the 15 ~ 20 ft range there should be no problem if the sub is tucked to the side or behind a piece of furniture. If you plan on putting the sub out to 60' away then yes you would need line of sight.
#2 Can you mount the sound bar on the wall so there is space behind the sound bar for a TV power cord to run behind it?
Yes. The wall mounting hardware does provide a small amount of room between the soundbar and the wall for cabling.
