Setting up accounts on Outlook 2011 – when should I use ‘On My Computer’? Please help!

My wife and I recently purchased a MacBook Air and Office for Mac, and I'm having trouble configuring her Outlook accounts so that she can sync with her two iPhones (one for work, one for personal use). She was previously using Outlook for PC, so she has brought a lot of data to the conversion. 

I can't understand where I should put her Calendar and Note information. Here is what I can figure out after talking to her:

1. She has an account for her company that is provided via a Microsoft Exchange server. Her company sometimes posts calendar information, such as meetings and appointments, into this account for all of the employees to see.

2. She also has a large amount of old notes and appointments that she doesn't need to share with other employees,  but are quite vital to her work. 

3. There is also a large number of personal entries in Notes and Calendar that she didn't classify, and she had previously entered these (in her PC version of Outlook) on her company profile. 

So my questions are:

1. Should I continue to use JUST her MS Exchange Server account for all Calendar entries, including personal things etc, or should I put personal things into the 'On My Computer' account? When, in fact, should I use the 'On My Computer' account? It seems that many people turn this off in Preferences. 

2. She can only sync up to her work MS exchange Server via wifi when she is in her office. Will this pose a problem when working from home?

3. Will her iPhone automatically sync up to the 'On My Computer' calendar entries by default? 

Thanks very much for your help!

Regards,

ANDREW