I recently went through a similar proof of concept corporate iPad deployment and had the same questions walking in. The direction we went might not be the best solution, but it worked for us and maybe it will give you a hand with your deployment.
Know your Audience
Early in our deployment it became glaringly obvious that this would have to be a simple solution. Apple devices are designed to be simple, that's the draw in the corporate world. Our main audience was managers, VPs, and CXX level executives. A good number of these folks either aren't technically savvy enough to deal with a complicated configuration, or simply don't have the time to fuss with a device.
It should just work, out of the box, like it was designed.
Just Say NO to Multiple Accounts
Firstly I can see one big problem with your initial plan. By stating that you have an account created with a secret password I'm assuming that you're having a helpdesk configure the devices and install the software before they're handed over to your end users. What happens when an application is updated in the AppStore? Your helpdesk will have to enter the password to have the application updated. Depending on the size of your company this could eat up a ton of time, and most of your end users most likely won't ever bother to go through the process to upgrade.
Additionally, when John Doe leaves the company, the software purchased for jdoe@acme.com will be assigned to John's replacement Fred Flinstone and his iPhone. You now have fflinstone@acme.com using the account jdoe@acme.com. It might not be a big problem at first, but this will easily get difficult to manage down the road.
Mobile Device Management
Depending on the size of your deployment you might eventually start looking at one of the many Mobile Device Management (MDM) solutions out there. We did. It's likely that things will change in the future, but as of this posting we didn't find much that an MDM solution would bring to the table that our Exchange environment wouldn't already provide.
MDM offers a simplistic way to deploy VPN, Wi-Fi, and user profiles. If you're not using Exchange or aren't comfortable with rolling your own solution you might gain more from one then we were able. Other benefits would be device tracking, and enabling your helpdesk to do basic device troubleshooting, device wiping, remote locking, etc. Read the link to Wikipedia above for more information and a decent list of the bigger vendors in the field.
Application Purchasing
We first identified a list of applications that we would recommend for different tasks, and published the list and relevant links on our company intranet. Initially we installed a few applications when we initially configured the device, but ran in to the time problem above. We calculated a total estimated dollar figure of all applications that an average user would purchase and bought gift cards for that amount + an additional X% for growth. This was more convenient for how we do purchases then gifting would have been.
Apple recently announced their Volume Purchase Program (VPP), and you might want to look in to that if the solution above isn't any help.
Further Reading
Best of luck to you, we learned that smart devices in the enterprise is a rapidly growing environment and there's no "right way" to do things yet. Apple is constantly improving their tools to make the transition better, but they're not quite there yet.
Using Numbers would work as you say it syncs when ever a change is made. The benefit of this is that it is customised to your wifes needs, i.e the filed Name, Instrument, etc, ect are what she needs.
Using Office to go adds a few unnecessary steps to the procedure, with iCloud everything just syncs.
If she were to buy a database package it is not likely to contain all the correct fields she requires and would contain a lot more that would be useless, so a bit overkill really.
However the benefit of having a database app like Bentois that all your contacts details are clickable on the app, so if she is looking for a bass player she will be able to search and then click the contact number to call them. However this has a much larger cost than just buying Numbers for iOS.
Best Answer
There are two separate questions here but hopefully they won’t get mixed if I’m careful about wording things:
So - If you really want to keep work from personal - sign up for and maintain a work AppleID so you don’t mix the streams. For many people, using a personal AppleID for just the App Store is super low risk and you can manage to not auto install apps and control what app history you wish to share with work. Without MDM, they can’t modify settings, wipe the device, lock the device, unlock the device. With MDM they can do those things, but you will see they can do it and ask about their policies so you can make a good choice.
I wouldn’t mix normal AppleID like messages or Photos or iCloud or GameCenter with work and pleasure - this answer just is about apps and access to app data. That second item could leak more data like contacts or conversations you would rather be yours.