Hey Denis,
I never migrated game files before, so my tutorial may not help you 100%. But as a warning, you might have to redownload Arma 2, Arma 2 OA, DayZ and DayZ Epoch, if you do not want to move all your Steam files into your SSD.
So... Firstly, I assume that you only have your C:\ drive, and that your new SSD is working correctly and you're able to access it. So now, we'll go right into the tutorial.
Step 1:
https://support.steampowered.com/kb_article.php?ref=7418-YUBN-8129 Steam's support website provides a how to move and install onto another storage location.
Basically what they want you to do is delete everything except for SteamApps and Steam.exe, copy SteamApps and Steam.exe from your C:\ drive and move it into your new drive. After you do that, you open up Steam, verify your files and then you're able to open up Arma 2/DayZ, etc. If you're happy with this, then you should have no issue logging into Beatniks Epoch when the transfer is complete.
Now. This guide seems to move every game you have into your new drive, so if you don't want to do that, then it might be possible to only copy your Arma 2 files from SteamApps, add it to your SSD, then delete your Arma 2 files from C:\ and go into Steam and try launching the game to see if you can change the file path and reverify Arma. Since the DayZ Epoch mod is in your Arma 2 OA file directory, you should not have an issue launching Beatniks Epoch.
If that doesn't work, then it's probably better to redownload Arma 2, Arma 2 OA, and the DayZ and DayZ Epoch mod to the SSD.
As for your character, items, base, and vehicles. You will not lose anything as character data and items are saved on the server and not on your local system.
Not sure if this helps you out, but it's a start.
_Edge
