I've become very proficient in MS Office on Windows PC over the years but am struggling on my iMac.
I think you'll be back up to speed pretty soon. I started with Word 3 for Mac (long before MS created the "Office" moniker for the bundled product). When I was working, I had both Mac and Win computers in my engineering office. Although my primary tools as a technical editor were the Macs, I relied on MS Access on the PC for working with the company's engineering databases, so did not have to worry much with any other Office apps on the PC.
When I retired, I started volunteering at a local museum and, because I could spell "computer" correctly 80% of the time, was bestowed the lofty title of "Chief Computer Basher." Unfortunately, the museum is all Windows! To add to the problem, they had Office 2010 for PC on their computers. I'm still struggling with finding stuff on Office's recent "ribbon" system. It seems they came up with a snazzy-looking interface without bothering to consider that someone actually had to use it!
After three years of Office 2010, I'm finally managing to find most of what I need in the tools tied to that interface. I'm still on Office:Mac 2008 at home because it maintains the older and more comfortable interface. If you have Office 2011 on you Mac, poke around and see if they is a way to restore the older style menus if you "grew up" on Office:PC 2007. I understand that option may be hiding there someplace. That should give you better parity between versions. It might be a question to ask in the MS forums.
Another thing that helps is to find as many keyboard shortcuts as you can in the Office Apps. They are often undocumented but you can find them for each Office:Mac app by seeing if a shortcut is shown in a pull-down menu or, in Word and Excel, by doing View > Customize Toolbars and Menus and clicking the "Keyboard" button at the bottom of the Customize window. That will reveal any shortcuts assigned by default and allow you to customize some of your own.