Could anyone who owns a whippet or just knows about this breed tell me a bit about them?

I heard they're energetic outdoors but a couch potato indoors is that true? Do you let yours off lead? If so how did you teach it to come back or stay near by without running off? I also read they sleep alot so im guessing they'd be alright being left home alone? And how easy are they to train? What do you use to train them? (treats or toys) And just anything else i need to know about them would be appreciated, thank you:)