For the mounting, do yourself a favor and get a couple of light-duty light stands that can extend to at least seven feet, along with a couple of tilt flash/umbrella adapters. If you don't need to support studio strobes with heavy modifiers, stands can be gotten pretty cheaply, and the tilt adapters can often be picked up for about ten bucks a unit or less. Not only will they be able to work with your light tent, you also be able to use them for just about any routine lighting setups you'll encounter. If a perfectly consistent setup with the tent is required, you can always mark the position of the stands and put witness marks (with a paint marker or a scratch awl, depending on the stand) on the risers and the flash adapter for later reference.

I'm not aware of any AC adapter that will work with the Yongnuos. Keep in mind that the current draw during recycling is very high, so the typical "wall wart" won't really be up to the task, and if the power supply provides a current that is higher than low internal resistance batteries can provide, you are likely to trip the thermal protection ciruit regularly (at best). Despite the inconvenience, you'd probably be better off with rotating (rechargeable) batteries through the units.