If the wheel is reasonably true, leave bad enough alone and ride as is. If it requires minor alignment, try putting a drop of liquid wrench or a comparable product on the affected nipples where the spoke enters, then spin the wheel to force it out into the nipples. Wait 24 hours for it to work and try to align the wheel.

There's nothing to be gained trying to replace rusty nipples. If they turn then they're fine, if they're frozen to the nipple they can't be replaced without the spoke also being replaced. So yes replace a frozen spoke and nipple or two if necessary, otherwise ride as until it's time for a complete rebuild.