Recording 4 impulse responses for 2 playback channels is confusing. You could easy use a 2 channel impulse response to create a 2 channel playback signal. If you get a more detailed look, you will realize that you have with a 2 channel IR 'only' signal from hard left and hard right. But in a mix, you have signal from right which goes to the left channel an conversely. So you get a more realistic and more detailed reverb signal if the IR-processor takes 4 IR Samples to create a reverb. Have a look in here: Recording Impulse Responses for mono and stereo playback
Creating your own impulse responses is a very creative thing and can make a lot of fun - if the things work correct. I got a lot of troubles and frustrations when I record my own IR's for my Impulse Response Collection.
The idea about my Impulse Response collection was to create new 5.1 spaces. I thought it's an easy thing, but in the end, it tooks about 4 month to complete it! And the multichannel IR's for Altiverb I have completed some weeks ago because Altiverb does not support multichannel deconvolving yet. I realized soon that creating IR's for more than 2 channel playback is not an easy thing, there are no tools for that and I had to find an own way. Apple's Impulse Response Utility which actually is designed for that has completely failed, it could not deconvolve it's own material!
For recording IR's I can give you this tips:
-Play sweeps as loud as you feel it is right for the room. If you play a sweep too loud in a small room, you get too much rumbles you don't want. If you play back a sweep too quiet in a large room, for example a church, you get not enough room response/reverb.
-Avoid distortions under any circumstances! Distortions can happen to single frequencies! Have a look in here in the spectrum of impulse response sweep. If single frequencies clips, it get's some weird an uncontrolled behaviors like negative phases and unstable signal phase in general.
-To find a good spot in a room: listen. Or think about: If there would be musicians in the room, where would you place them to get a nice sound and where would you place the microfones for that.
To mix and adjust levels for IR's I have used TL Space. TL Space is not that smart than other Convolution Reverb Plugins, so you can add an remove IR's whenever you want and TL Space will playback it. But be careful: TL Space has a bug and mixes up channels! Another disaster which costs me a lot of time to find that out.
More infos about recording your own IR's you can find at my tutorial. It's only part 1, if I find time, I'll complete it once. But I don't know when.