Newbie questions

I'm new to the CHL world, not new to firearms. I'm very comfortable with them in general. I went to the range yesterday and rented several subcompacts and have firmly decided on getting a Shield, completely fell in love with that gun. I shot a G43 and hated the trigger immediately, really liked the sig p938, XDs was meh, beretta was meh. Looking around based on price I'm going with the shield.Question 1: safety or no safety? Like I said, I've been around firearms my whole life and have good practices, just the back of mind having a safety makes me feel more comfortable to carry a gun, but I didn't care for the safety on the shield and think it may be hard to turn off when SHTF.Question 2: AIWB? You guys seem to love it and it makes sense to me. I don't have too much of a gut but I spend 4-6 hours a day in the truck minimum so I worry about that some but not a ton. Typical dress for me is a tucked in button down with jeans so I think it would be easy for me to adapt carrying with my current wardrobe. I'm pretty much set on stealthgear for my holster and I like the looks of their AIWB. Would this be ok for a newbie to start out that way or would it be too risky? 4-5 o'clock seems fine too but AIWB seems like a no brainer.Question 3: 9mm or 45? The shield 45 is only marginally bigger than the 9mm. My other pistols are 45 and I'm comfortable with the round. However I'm having a hard time finding the 45 for sale. I found it in one place but it was for law enforcement only. Are they having supply issues? The argument has always been you can carry more rounds in 9mm and it's cheaper to shoot, but the capacity is the same on the shield and only 1cm difference in frame width, 2 ounces in weight unloaded. I know this is an age old battle and I've seen all the data on new round performance so I know the 9mm will be equally effective. Just want some thoughts. I shot the 9mm yesterday and it was fine, haven't shot the shield 45. via /r/CCW http://ift.tt/29VYJ6S