Many of your questions are answered in other threads on this board, I suggest just spending a bit of time reading some of the other threads.
>> What is the best version? Is there a "Professional line" of FTM?<<
There are two versions of FTM for MAC, the latest version "syncs" with the ACOM on-line member tree program. No "professional lines".
>>4. What happens when FTM comes out with a new edition of the program? Can I upgrade to the new version and keep all the documents? I want to be saving the documents them selves, not just the info as in a GEDCOM file.<<
Yes, you can upgrade to a new version and your data from the older version upgrades, as files to when you upgrade from one version to the next with any other application.
>>If Family Tree Maker is not the right program for me, can someone tell me that program that would answer my needs listed above. I prefer Mac to PC programs.<<
Only you understand your needs. If you want to have the ability for the ACOM on-line tree program to share data (relatively) in-tact with a desktop application, FTMM might be a good choice. I say "share" data because the desk-top FTM/FTMM and the ACOM on-line member tree program are not versions of one another, they have the ability to share SOME data, but not all. The ACOM member tree program is not a full blown bells and whistles genealogy program, it's limited in functions it offers., FTM/FTMM are full blown gene apps.
If you have a Mac, get a Mac native program. I use both FTMM and Reunion, up and downsides to both.
>>3. Does FTM work using ancestry.com records?<<
Yes, but using the web-browsing function (including the Ancestry site) from FTMM can be slow, clunky and buggy. If you work with a number of tabs open to the ACOM site, you should be directly on the site.
>>1. Is the tree cross-referencable? For example: I have a lot of family buried in a cemetery, can I cross-reference to see all the family members buried in that cemetery, or do I have to look at each person individually like with Ancestry.com?<<
Not sure what you mean. Your "sort" options are limited on ACOM, whereas in FTM there are many more choices to sort and also run reports, which ACOM member tree program doesn't do. Again, ACOM member tree program is a very basic gene app, with limited functions.
Most of what you read on this board is about the dissatisfaction with FTMM, however there are very few issues that can't be resolved. It helps if you understand this kind of integrative software is pretty delicate, and not suitable for novice users (to Mac, to genealogy applications, to using the internet effectively, to ACOM; or any combo of those), not without spending a good amount of time learning all the tricks of all the players.