C.C.
I have used Outlook forever and a day (seriously, the last 15 years), and have used both Blackberry and iPhone without any problems. It works best if the Outlook is hosted on an Exchange server (otherwise, you have to delete emails on both the phone and the computer, which is kind of a hassle, and whatever you send on the phone doesn't show up in sent messages on the computer, and vice versa). But even without an Exchange server involved, it should still work (i.e. receive emails on the phone, calendar updates, etc).
My recommendation is for your husband to ask around at work and see if anyone can help him set up his email on his phone. If there's an IT department, someone there can set it up in a matter of 10 minutes. That is what I've always done. :)
In terms of which actual phone, I was a Blackberry girl for 10+ years and thought I could never live with the lack of keyboard on an iPhone. I finally made the switch about 2 years ago and after about a week of struggling with the touch-screen typing, my fingers figured it out, and I haven't looked back. I would whole-heartedly recommend the iPhone for business use, even for someone who thinks they want a "real" keyboard. I hope that helps!!