Excel for Mac 2011 is pretty similar to Excel 2010, but it does not support add-ins and has very limited macro support.
Apple has something called AppleCare that you can buy that gets you better support, but it is pretty expensive.
Yeah, I had a hard time believing that it would be any worse really, but maybe it's only older versions on Mac? Or (more likely) that older versions on Mac aren't quite as compatible with newer ones on Windows. I've had to reformat and fix a lot of the templates I've made for people. I wouldn't consider it a deal breaker by any means though, even at it's worst.
As for AppleCare, fuck them. I can understand it on the iPhone to a point, but it's pretty ridiculous. You kind of have to see the iOS games thread to see what I'm talking about, but I bought an iPod Touch 4g like a week ago. Nike+ doesn't work, and it's a common issue. So, I tried to get a hold of Apple to be like "what the fuck? Are you fixing this or am I returning it and buying a Garmin watch?" They wanted me to pay $30 to talk to someone on the phone, specifically because I didn't buy Apple Care. Like, I'm not even making a warrenty claim or anything here, at most asking for a support ticket and the website wants $30 before I get a phone number.
*There's a chance that I may have been in the wrong place, although I doubt it because I thought about it and went through twice.