I agree with the stuff that Jack said. In addition to what he said, I would add the following:
For audio, if you’re going to use lavs, you can use the RodeLink Wireless Filmmaker Kit, http://www.bhphotovideo.com/c/product/1115091-REG/rode_rodlnk_fm_rodelink_wireless_filmmaker_kit.html. If you have it in the budget to buy 2 of the kits, both mic packs can connect to the same receiver pack, or so they’ve said, and, theoretically, you can have the already mixed audio going into the same input on the camera, which will save you a step in post having to mix the left and right channels from having separate systems plugged into the 2 different inputs of the camera. Personally, I prefer to have a person running a shotgun mic, so that you don’t have to worry about hiding the lav on the actors. If you can get that extra person that you talked about, I would recommend they run a shotgun mic for you.
As for the lighting, you may consider simply bouncing light off the ceiling and walls. If you can make this work, you can use minimal light fixtures, and your light will already be diffused. This, of course, may not work for you, depending on what your goals are and what kind of look you want. But if it will work for you, it’s extremely easy, and cheap, to do.