Can your mobile phone get a virus if you use it as a modem for your computer?

Answer 1

Not directly, no. When used as a modem, the phone is just a carrier; it doesn't execute anything from the traffic that passes through it.

Theoretically, however, if your computer becomes infected during the connection, the malware could, in principle, detect that a phone is attached to it and infect this phone with some phone-specific malware. But currently no known malware exists that would do such a thing.