Just ask, don't push it, if they want fiat give them fiat just ask them if they know about Bitcoin and make sure you don't fuck them.
Yeah, ask them if they want it, and if they show some interest explain what it is. Don't shove it down their throats or it will paint BTC users in a bad light. Also, you do run the risk of them accepting it and it crashing and then they blame you. Make sure you disclose its volatility so they are fully aware of the risks.
Definitely. You don't actually have to force them into it but at least, give them a bit knowledge of how bitcoin works if they are willing to. If they don't, then so be it. Forcing them is not needed.