Telephone, computer and privacy



I have two similar questions:

1. My phone is connected to a modem, which is plugged into a wall telephone socket. Does this reduce my privacy vs an actual landline which has the phone plugged directly into a telephone socket (I have heard that people could stand outside a door or building, and with certain equipment, listen in on all wireless phone calls)? My telephone company has been less than helpful which may be due to lack of training or they just don't want to tell me the truth.

2. My computer is connected to a wireless modem router which was plugged into a wall socket (like a telephone plug). I bought the modem at a local electronics store. The building I am in is wired for WIFI. Could people monitor all my online activity (similar to a wireless phone), or does this only happen when you plug a laptop into a WIFI at a local coffee shop, etc? If this can happen under my circumstances, how do I protect my privacy when all buildings are being wired for WIFI? My ISP has been less than helpful for the same reasons as above.

I wanted ethernet but apparently you can only get that through cable. The cable company has already been to court for violating customer's privacy and is the company that wired the building for WIFI.