From dictation, there may be some typos here.Here is a general answer to your question. It looks like you are asking three questions at once. So I'll give three answers.
1. Windows may or may not require a password when you log into the Windows-based computer. The password does not guarantee that the files on the computer are secure. The password only prevents somebody from easily entering your computer while you are out to lunch.
2. Many websites do not require any kind of security features for most kinds of browsing experiences you are likely to enjoy. However, whenever a website requests information from you, such this a
credit card number, a secure connection should be established. Normally your browser will inform you when there is a secure connection in progress. It is very difficult for anybody to ease drop on a secure connection because all the data is scrambled according to an encryption key that is known only by your computer and the secure server that you are connected to.
3. Now about Wi-Fi. Nowadays Wi-Fi connections require a password and also there is some type of encryption method. This prevents anybody from ease dropping on the wireless transmission. However, this does not guarantee that the transmission is secure over the Internet, it only secures the wireless connection.
Now about the problem you have. You need to check your router's manual to see if the router has any way to secure password protection of the USB port. If not, you're going to have to implement some kind of password protection on the hard drive that is connected to the USB port of the router. Sorry I don't have a quick answer for you as I have never attempted to do that sort of thing. However, here is an alternative idea.
If the amount of data you want to share with other people is moderate and you don't want to leave your equipment turned on day and night you may consider a cloud service. In brief, a cloud service is a file sharing service that's on 24 seven and requires a password to access. It works even when your computer is off-line and your router is off-line.
The cloud services actually somewhere on some other server, maybe even in a different country. The services password protected and the people you want to access the cloud service will have to have the password that you provide. Some cloud services offer free file sharing up to about 10 GB.
If you are interested in the free cloud service, you can just check it with your search engine and use the expression" free cloud service".
That's the best I can do for you.