What you like to do ... there is a working SSH / SSL already on your Mac. If you like to build stunnel you need Xcode with the CLI tools ... and some time. I haven´t tried it but a quick look in the build instructions looks as if there are no big problems.
As promised, here are the steps to build stunnel from source. I used a Lion machine but it is the same on a Mountain Lion machine. There is no need for Fink, MacPorts or Homebrew ... brings more troubles then it helps.
Go to https://www.stunnel.org/downloads.html and download stunnel-5.23.tar.gz and stunnel-5.23.tar.gz.sha256. Open a terminal Utilities => Terminal>. Terminal is case sensitive, before you do something think twice before you press return - there is no undo or redo in terminal. Each line is one line in terminal and needs to press return at the end of the line.
cd $HOME/Downloads
openssl dgst -sha256 stunnel-5.23.tar.gz
more stunnel-5.23.tar.gz.sha256
Compare the output of the last 2 lines - if it matches all is fine, if not you had a security problem during download.
tar -xzvf stunnel-5.23.tar.gz
cd stunnel-5.23
./configure && make && make check && sudo make install
The configure script uses autoconf, so put your fingers away from other options because if all is there and supported it will build a fine 64 bit app for you. make check is optionally. sudo make install requires your admin password. During this step you had to input some basic informations (self explaining). The && is used to run one command after each other ONLY if the last was successful.
After all is done your stunned app was installed in /usr/local/bin. To run it, open terminal and type stunnel or stunnel3 (see the docs for the difference) and press return.
For the config file type in terminal.
cd /usr/local/etc/stunnel
sudo cp stunnel.conf-sample stunnel.conf
sudo pico stunnel.conf
For the documentation of pico use in terminal.
man pico
If I had some mistypes of filenames or anything else here use in terminal the following command to list a directory
ls -la
For the rest, have fun with stunned and the documentation of it !
I always do option 3. You should be able to pretty much follow these directions, even though they reference Lion: http://forums.macrumors.com/showthread.php?t=1189888
Long story short: When you buy an app from the app store it is stored on your drive in a format that can be burnt.
Of course, the USB drive option is also doable and it sounds like that would be easier for you.
Best Answer
1) No. Safari requires libraries and frameworks that will only be found in Mavericks. You can potentially snag the Safari.app from someone runnin v7 on OS X 10.9, but I'm fairly certain it will simply crash on launch due to the requirements mentioned above.
2) Yes you can still install Mavericks provided you have purchased it from the Mac App Store. It will be listed under your Purchases tab.
3) No. You will likely suffer the same discrepancies mentioned in 1) with a version mismatch.