So if I'm understanding you correctly, you want your work and home PC Outlook calendars both synchronised so they are both the same? You also want this synchronised with a Googlemail/Gmail calendar? You then want that synchronised to your iPhone? And you want to keep your colour coding?
All easy except the colour coding, as I'm not sure if that will work. However....
Two options.
Option 1:
1) Install this on BOTH PC's:
Getting started with Google Calendar Sync - Google Calendar Help
2) Use the 1-Way Sync for the first pass on both PC's, so the contents of each are uploaded to Google Calendar
3) Change it to 2-Way Sync after both have uploaded their contents to Google Calendar
4) Configure your iPhone to Synchronise with your Googlemail calendar using Google Mobile Sync, as per here:
Google Sync on your mobile phone
This has effectively given you a eight-way sync. Anything you enter anywhere is automatically synchronised to everything else.
If anything is going to go wrong in this process, it will be getting the contents of both PC's (Outlook) uploaded to Google. Worst case is you end up having to do a big clear up operation to remove duplicates.
Option 2:
Stop using Outlook and use only Google Calendar online. Manage everything through here and use Google Mobile Sync to keep your Google calendar and iPhone in sync.
I'd guess Option 1 will be your favourite, but Option 2 is infinitely simpler and less complicated.