Real estate looks as if it is way over-priced at this point. If you don't want the tax benefits of owning a rental, why not index fund your money, then you would be almost double the 4% long-term, either way.
I agree a lot of hot metros are looking expensive (SF, Seattle).
Things are cheaper in places farther from growth and money, e.g. rural Indiana. I'm not sure whether they're better deals on balance, but quite different.
Every market. Literally every market.
probably a small part, to be fair, especially if you own your own home