If that were me in his position I'd stick with something the size of the LC9/Shield/Glock43 range of guns possibly the Sig 365 anything that size that he likes the feel of is likely a fine choice pending it's reliable even the PF9 isn't something I'd ignore(I've had good luck with mine over the years, and it's still my only gun that will feed empty cases from a magazine). Then likely a single mag weak side since capacity isn't a strong suit, and actually if it were me I'd lean towards the single stacks of the LC9/PF9 and less towards the 1.5 stack of the Shield and thicker mag of the g43. The single stacks are almost non existent in an IWB setup and make them so much easier to carry.
Rig wise again if it were me I can tell ya what I'm wearing tonight which is my PF9 in a Texas with a Switchback single mag carrier weak side. Only reason was I had to run to town for my mother in laws birthday earlier and just was honestly lazy and wanted something that requires zero work to carry and conceal. Adding to that I lifted my water softener tank last night and my back is less than happy about it;)
Now alternatively if I didn't make holsters, I'd be looking at possibly a hybrid holster of the same size though stick with something not too expensive. On the mag carrier I don't have a good recommendation, the vast majority just aren't very conducive to being comfortable IWB, probably OWB if he needed to go cheap and likely a simple clip style affair is the best approach.
I can say this though based on my own experiences, mostly designing bad holsters that people will never see;) I've designed some IWB versions for the PF9 which is immensely easy to carry in a Texas that are incredibly hard to carry comfortably. So all rigs aren't created equal in that sense, and if he does decide to go cheaper or faster etc, feel free to send me a PM for a critique of the rig and whether it looks like it's worth the cash or has any serious issues I can see or know about. I try not to criticize other holsters but if guys want a no BS assessment from my perspective I don't mind giving it, I just don't want anyone to think I'm pushing my own agenda. I do think my rigs carry well, they aren't the only option, but I've also spent ALLOT of time looking at what is out there;)
Take care!
Luke
EDIT: I also should mention I see this as a "First" gun of sorts, for carry. It covers the bases gives him something that just works. Then if he wants a full size or something larger with more capacity he's got an option to fall back on. His size though is likely to be the biggest trouble with carrying larger guns, they might require more compromises on the clothing as well as the size of the gun. For instance I suspect a 3.5in or 4.25in 1911 would be a much better fit than a 5in. for his size. Just the facts of size and size of the gun, guys carry guns bigger than they need to at times, I'm guilty of it. But the size of the person is going to play a role in what is easy to carry and conceal;) So a smaller single stack is a great way to know you can carry whenever, then you can run something bigger if things work out. Like winter weather and heavier clothing etc, but that PF9 sized gun should be good to go in shorts and a t-shirt all the way up to heavier clothing so it's the broad approach;)
