Gmail, outlook express, Yahoo mail, and my iPhone
	
	
		Okay, I don't understand all the computer lingo so please be patient with me.  Here is my scenario:
I just got a new job.  I have a personal email on yahoo.com.  I also have an account set up on gmail.com.  In my previous job, I had all accounts going into Gmail, a program  which I like very much. 
At my new job, they try and use Outlook.  Here's my issue.  I want to have our Office Manager who sets up our appointments be able to access my Calendar and input them there.  I would like to be able to view this from my Iphone.  I would also like to be able to go to one source for all my emails, not have to log-in to gmail, Yahoo, and Outlook.  
What is the easiest way to make this scenario work?  Thanks in advance.