I usually don't go as far as using crystals in my projects. Ceramic resonators are plenty accurate enough for most projects. After all, the UNO only uses a 16MHz ceramic resonator for clocking the '328P. The crystal on a UNO board is only for the ATMega16U2 chip that's used for USB to TTL conversion. And if you get 3-pin ceramic resonators, you don't need additional load capacitors.
You can also use the internal 8MHz oscillator, of course. That's what I mostly use for clocking the ATtiny chips, to free up the extra 2 pins. The internal oscillator isn't as precise as an external resonator or crystal, though.
Probably true, but I'm old school and I follow the breadboarding tutorial I linked religeously , using crystals and 22 pF mica caps from DIPMICRO.COM where I get my ATmega328s. I've got half a dozen breadboarded ATmega328s working and never had a problem. You can probably use an internal PLL oscillator in the ATmega328 but I only use those for ATtiny85s.