1. I'm not sure about the model, the plate says: FSD7230-4 but it has 2 antennas like the FSD7231. 2. How can I configure DynDNS so my file server at home is reachable via internet?

There are a couple of ways of doing this. Here are a couple of my favourites. All of these require you keep your computer on.

1. Opera Unite
If you install the freeware browser Opera, then create an account with them, you can start Opera Unite, an online service for accessing files and services from anywhere. After you have added the File Sharing application from the Unite sidebar, you can configure the application. Choose to add a share location and choose your main hard drive (generally C:). Then, change your password and make sure that you set your Opera Unite account to private and check that File Sharing is password-protected. Then simply navigate to the URL that Opera provides (generally username.operaunite.com), enter your username and password and then you'll have full access to your files. Note that you will need to keep Opera running on your Computer

2. FTP server. *Only recommended for advanced users
By running a FTP server software like FileZilla on your home computer, you can create a far more powerful file sharing experience. Now, first up, you should go to DynDNS.com, sign up for a free account and then create a Dynamic DNS host. Next, download and install the DynDNS Updater and run on your computer. Now, to access the files that you have configured with your FTP server software, simply use your DynDNS hostname that you created in the sign-in process into Windows Explorer or Internet Explorer (or any browser) with the ftp:// prefix instead of http://. However, if your computer is on a home network behind a router, you will need to configure that also. Set up a port forward (generally Port 20,21, and 23) to the computer running the FTP server. The other advantage to this is that by finding out the server's local IP address (open Run, then type cmd, then type ipconfig, and write down the IP address shown) you can also access the files from the server within your network, simplifying the file access process greatly.

3. Orb 2.0
This is one of the slickest and smoothest methods. Simply download and install the Orb desktop client from Orb.com (also create an account and enter your details into the Orb client), then add any folders you want to share. Then, allow some time for it to index your content. Now, from outside your network, log in to Orb.com with the account you created and click on the Applications button at the top of screen. If you want the music, videos, photos or documents you specified in the setup process, choose the appropriate application, or choose File Sharing to access all of your files at once. Simply navigate the folders as if it was your local computer and you will be able to use them flawlessly. You can even access other physical drives like your CD drive online.

4. TeamViewer
This is a brilliant VNC replacement application. Simply create an account, then install the client on your computer. Also, enter your account details into the client (click the button at the bottom right of screen) and write down your 12-digit ID and password. From here, you have several options remotely. I recommend that you should link up your account first. Navigate to login.teamviewer.com and login, then add a client using the ID and password from your computer. Now, whenever you login to your account, you wont have to remember your ID/password. You can install the client on another computer and connect with your account directly or login to teamviewer.com and use the Java-based applet to connect and use your computer as if you were in front of it.

These should work well when accessing your files.