Yes, a US citizen can marry an illegal alien whose Visa has expired in San Francisco. The illegal will still have to renew their Visa to stay in the US.
In most countries, especially the USA, even if the passport expires, no problem. You can renew the passport or get a fresh one. The visa must be valid and should not be canceled or mutilated or damaged. Only one passport must be valid. The valid passport and the passport containing the visa - both - should be issued by the same country. Most countries have the same rule as above.
No he must have to renew his visa by applying again.
No, because you have to renew the Visa outside the US. The state recommends to renew in the homecountry, but Canada is also possible. Once it is expired there could be several problems to get back in the States.
?
No, you cannot board a flight with an expired passport, even if it has a valid visa. You must have a current and valid passport to travel internationally.
No, it is not possible to stay in the country if your visa is expired. You must renew your visa or leave the country before it expires to avoid legal consequences.
An illegal alien.
If your visa is expired, you must renew it or be faced with deportation. The two circumstances mentioned in the question have NO bearing on one another.
No, you cannot fly domestically with an expired visa. Domestic flights within a country typically do not require a visa, but you may need a valid form of identification, such as a driver's license or national ID card, to board the flight.
Yes, the visa is still valid, but you will have to bring both passports (new & the expired one) every time you use visa.
Not officially.