I think you're making a very solid decision for a first/HD gun. I was in your shoes not long ago and looked long and hard at the 4" GP100. I ended up with a used S&W Model 10 instead, but that was only because money was tight at the time. I lost the ability to shoot .357 but I saved about 300 bucks in the process. I had planned to upgrade to the GP100 when I had the money but I just love that Model 10 so dang much. It's likely going to stay with me forever.
As for the S&W Airweight you said you'd like to get for CC, definitely look into the Ruger LCR as well. I did tons of internet research on the perfect CC revolver and I was pretty dead set on an Airweight. But when I got to the gun store and had a chance to actually hold it in my hands, it just didn't feel quite right. The guy behind the counter said he felt the same way about them and much preferred the LCR. So he let me check it out and I was in total agreement. It just felt better in my hands, but of course your mileage may vary.