The current use of simple logic gates
For you second question, parts such as TI's 7400 NAND show as still in active production. They wouldn't be being manufactured if people weren't using them in large volumes.

There are many places where they might be used, whenever a circuit designer has a need for them. I know that may seem unsatisfactory, but there are billions of products out there and millions of different designs and applications. It would be pointless to speculate what might have them.

I will leave you with one example that I know of - some vent fans in bathrooms/toilets. This might seem like an odd place for something like that, but in fact they are used to form a simple oscillator circuit with a capacitor feeding the input of a chain of NAND gates. This can then be used for timing of auto-off (ever wondered why the fans stay on for a few minutes after you turn off the switch?).