Alot of questions, but it all boils down to security.
Simply put, wireless has to send data over the air. To better understand what it looks like, one needs to get a PACKET SNIFFER.
I suggest you try one of these :
Any one, just run it and then use a browser and your e-mail client. Then look at the data. It could be very large, but examine the data.
You will see some stuff you would NOT really expect to see. Using an e-mail client, either on your computer or even the web. UserID and P/W is sent in CLEAR TEXT, that means you can READ it. Some goes for that bank or this forum.
So what is SSH? It is another form of encryption. Anything going out gets encrypted on your computer and then it goes to your Proxy server, your router, which decrypts it and then completed the process. Anything coming back goes to your router, get encrypted. then if in a WiFi hotspot to that place to your computer, or if home direct to your computer, which decrypts it, and you are done.
Yes, this takes time. You'll see a performance hit probably. More so away from home than at home.
Does this protect you, yes, more that you were before.
However, if you don't do banking in a WiFi hotspot or get e-mail, or make credit card purchases, your exposure is less. For many people this is not the case though. Working with 'sensitive data', same thing. But how many corporate people use SSH?
There are programs that use SSH for FTP, TELNET, etc. only. The server you connect to requires it and you have a client that does it. It just encrypts/decrypts the data for you before sending it out and when it comes back.
What are the chances of that 12 year old kid sitting in range of the signal you send out? What are the chances he has the 'power' to capture all the signals going out if 12 people are transmitting? Actually, he only needs to get the 'important' packet. This is why some banks use multiple pages for sign-ins. That way your UserID and P/W can't appear in the same packet.
Can someone sit outside your house or apartment and capture the data? Sure, but in that case since it might be a single stream of data, it would be easier to put '2 and 2' together.
Does this happen? I don't know, but it can theoretically. READ THIS for instance.
If there is a form of protection on the connection, WEP, WPA, WPA2, etc. the task becomes harder. However, if the key/passphrase is known the task becomes easier, just not in real-time, but computer can easily translate it if one knows how to do it.
Anyway, some more reading for you :
In most cases, your risk is probably bigger if you keep personal information on your laptop and it is stolen. However, the RISK is there... I'd say the risk is bigger at an airport, a couple of gates, 3 to 4 hundred people sitting around, many using laptops, tablets, etc. and all you need is one capturing the data flying around. Compare that to the number of people at a Starbucks...