No. Of course Google knows your searches, and can track your visits on sites that use their ads - they can do that in any browser. If you leave Google as default search engine they may also know what you typed into the address bar (due to suggestions) ... other than that Opera does not report to Google.
What version of Opera are you using ?.
If it's the newer Blink version of Opera (15.x-23.x) then you could try looking on the Chrome webstore https://chrome.google.com/webstore/category/extensions for an equivalent extension.
You will need to install the 'Download Chrome Extension' https://addons.opera.com/en-gb/extensions/details/download-chrome-extension-9/?display=en first, which allows you to install compatible Chrome extension in Opera.
Opera 12 does that. Opera since 15 uses a different rendering engine, and they decided not to force anyone to upgrade from 12 to the new version. But if you visit the Opera website, you will have a hard time finding a link to download 12.16 ...
Actually, I see in the change log for 23 that they are adding H.264 and MP3 support in Windows, hopefully that means Mac as well. Beyond that, don't know what your abbreviations stand for. Opera 12 intentionally supported d only open standards like Ogg Theora and VP8, but they seem to have decided to include all the popular ones now.
Opera - since version 15 - is based on Chromium, and is not considered as an update of the 12.x and earlier versions. It doesn't yet have all the features of Opera 12's Presto engine, but it is faster and handles problem websites better (especially web apps like Yahoo Mail and Google Docs).
Some of Presto's features - like MDI in Windows, I know Mac never had that to begin with - are not possible in Chromium. Some features (Bookmarks management) they have decided to leave to extensions - if you want it, then search the add-ons site to find one you like. I'm not sure what the status of Fast Forward is, but it may be another one they figure is better handled by an extension.
I replaced with opera 21 and all mail vanished
Opera discontinued their old Opera browser and started a new one. The new one doesn't have mail.
is there a way to save retrieve my mail.
See the "short of that, you'll need to fix your mail folder" part in this comment.
where does opera store mail
This will show you all the mail folders involved with mail. To find the location of your mail folder and preferences folder, see "Menu -> Help -> about Opera".
No Opera installer will remove Opera 12.x and earlier and its files from your system.
The default Opera profile (where your bookmarks and other personal data are stored) is inside a hidden folder. That's probably why you can't find it.
Opera 21 has support for bookmarks under the hood, you can enable a "bookmarks bar" in the main settings page. To manage bookmarks in the "root" folder (above the bookmarks bar folder) / to have a button to access it via a menu, an extension must be installed.
There's a way to import your bookmarks. If you're unable to use the bookmark importer from the menu "more tools" you can find instructions on how to enable it here - they're for Windows but you can do just the same on Mac OS X command line terminal.
I don't think there's a way to import the sessions (also, there aren't sessions anymore, only Speed Dial folders, bookmarks and Stash in the new Opera). You could open them via the old Opera and bookmark all the pages into different folders using its bookmark manager, then use the import trick above.