I have use several USB interfaces and had good luck with the M-Audio Audiophile USB and one the Edirol UA-25. Both can record at 24/96 with proper drivers installed. The Edirol has the advantage that you don't need special drivers if you only want to record at 44.1 or 48 kHz; it uses the Mac's built-in Core Audio functionality, which is quite good.
For recording software, I have used CD Spin Doctor, the recording software that comes bundled with Roxio's Toast, as well as Bias Inc's Peak LE. The latter is a high-end professional package with some of the more exotic features disabled. Given its ancestry, the quality of the active features is excellent. I think it runs around $150 (compared to $500 or more for the pro version). From a practical standpoint, it has a recording timer, so you don't have to be there when the record stops playing. Without this, the software would just continue filling up your hard drive with the sounds of silence until you get back to turn it off. I have not used the Audacity fee-ware, but I have heard good things about it.
For getting rid of pops, I highly recommend Bias Inc's Sound Soap 2.0. It seems to be able to recognize these very fast transients and take them out without disturbing the rest of the music. It also can take out background noise, but there it has a harder time distinguishing signal from noise and you lose some of the ambiance of the hall, etc. This is a problem with ANY approach to background noise removal and is not specific to Sound Soap.
Good luck!
Bill