Don't come to her with a grand plan all laid out, that will make her feel like she doesn't have the opportunity to develop this idea with you, as a partner. Maybe she would *want* you to start dating right away, for instance, maybe she will have completely different thoughts. Just bring up the subject, say you've been doing some reading about non-monogamy and you realized that you actually like the idea of her maybe dating other people down the line, and maybe you doing so too at some point, and want to know what she thinks. Then let the conversation go organically from there.
Good resources on jealousy at www.morethantwo.com
In terms of safer sex, you *do* have to define what that means. Condoms for PIV and/or anal sex is a given, but what about condoms and/or dental dams for oral sex? Gloves for fingering? Where would you want to draw the line? And as for emotional intimacy, it's more than just a question of is it ok for her to fall in love with someone else, what if she, or you, want to turn a dating situation into a co-primary partnership... another person to share your lives with? What level of commitment is potentially ok? Again, something you and she need to talk about together, and your ideas may change over time, but it's worth at least being aware of the question now.