macosmessages
Is there any way to easily one search in the Messages App on MacOS within one conversation? Across "conversations?
"Find" seems more for finding participants in conversations.
Any easy way to export a conversation (or all conversations) to text files?
You can change the shortcut for "Close Conversation" to something else, that should avoid the conflict. To do this, open Keyboard Preferences, and then go to the "Keyboard Shortcuts" tab. Click Application Shortcuts, then the + button to add a new one. You should get a popup like this one (I'm still on Lion, but I don't believe they changed much):
Change the application to Messages, enter the proper menu title (if it uses an ellipsis, you may have to enter that exact character — not just three periods — by hitting optionshift;), then enter in a shortcut you're unlikely to use.
It's also possible to disable a keyboard shortcut from the command line, rather than just setting it to some obscure command. However I haven't tested this on Mountain Lion or Messages app, so no guarantees.
If you're comfortable with the command line, the proper command would likely be defaults write com.apple.Messages NSUserKeyEquivalents -dict-add "Close Conversation…" nil. However I don't have access to Mountain Lion, so the com.apple.Messages part is just a guess. You may want to test first by trying defaults read com.apple.Messages and see if it pops up with an error. It should spit out a long list of plist-formatted preferences, if it doesn't the app identifier (com.apple.Messages) is probably wrong, so you'll need to do some digging to find out what it is.
Again let me stress that I haven't tested this second option on Mountain Lion or Messages at all, it's just based on how things work in previous versions of OS X.
Is there any reliable way to force Messages to refresh or reload the current conversation? Or make it receive messages reliably in the first place?
No. Messages is very buggy for many users and there is not a known fix at this time. I believe the most prominent client-side issues are resolved in Mavericks, but I am not running the it yet so perhaps not.
As far as I know, the best solution is to sign out of your account, log back in, and then restart Messages. For me, this fixes the ordering of messages (so they are sorted by timestamp) and generally keeps Messages running smoothly for a little while. However, the fix doesn't seem to last longer than a few days.
Best Answer
There isn't a "Search" or "Find" feature in the iMessages app for mac in specific conversations. Only all conversations.
CMD+F is the shortcut to search within the app.
To print/export a conversation, CMD+P will allow for a print view, but in the bottom left you can change from printing to saving as a PDF, etc.