Jim,
I've never used a 'Mac' so can't tell you anything about that part of it. I can tell you the general ideas though. Very basically, you want to feed output from a radio to the input of the sound card (interfacing). The software turns that input into something the saound card can recognize and handle. The output from that sound card is then fed back to the radio to be transmitted (more interfacing).
A 'RigBlaster' takes care of the interfacing, keeping levels at the right level, and preventing any RF from getting where it doesn't belong (hopefully!). The various interface manufacturers that have been around for a while at least know what should be done to accomplish that interfacing. There are so many different combinations of PC's and radios that one single interface won't work with all of them UNLESS there are provisions for making changes. That's typically why those interfaces are so expensive, just getting the input's from here to there can be done very simply, but the RF thingy is the part that's not easy, along with the different radios and PC's, sort of.
I'm not a programmer by any stretch of the imagination! So, deciding which software to use is as big a mystery to me as it may be to you. I've found a few programs that I can 'live' with and tend to stick to those. (Which doesn't say I don't try new stuff when I find it.) And since I don't 'do' Mac's, you are on your own.
)
Computer controlling a radio.
I don't care for it. I figure it's just one more step that can go wrong, and I don't have a computer with me all the time so that's a problem. I also like twiddling knobs and things! It's the same things you contend with as above, interfacing, the right commands to do what you want, and knowing what the #3:: you want to do to start with. Most radio manufacturers that allow for computer controlled radios usually give you a list of commands that work with their products. Some offer programs to do all that commanding too, some free, some not. There's also the 'after market' programs which typically do a little more than the manufacturer's programs. Again, some free, some not. Best advice is to take a look at what each program can do, and decide what you just absolutely have to have.
I figure you already knew most of this so take it just as a reminder. You almost never find the 'just right' software to start with, so try things till you find whatever is best for you.
Good luck!
- 'Doc
(I ain't giving you all of that 'luck', I need it too much!)