Rob,
In the studio, you'll want to go wider, rather than longer. The 50mm could be all you'll need for most of the shoot, but I don't think you'll need the 70-300mm as much as you'd need a wider angle lens. It looks a little odd if you keep having to take steps back in the studio, because you're using lenses that are too long. You also may trip over wires and other objects! Some shots just won't work and you don't want to be in a studio with a great model and realize there's a shot you can't get. You can always crop in post, but you can never go wider.
When I use FF, I usually go to a studio shoot with just my 28mm and 85mm lenses. I don't currently own a 35mm or 50mm lens, but those would be handy too, much better than a tele zoom. I highly suggest taking a lens in the 18-28mm range for use with your D7100. I rarely see other photographers with long zooms at the studio shoots I attend. On my crop factor Samsung, I primarily have a 45mm lens attached. Just make sure you don't get too close with a wide lens (definitely no headshots), as some photographer's are guilty of that and it distorts faces. Stick to using the wider lenses for half or full body shots.
A tripod is not necessary, but it might be best to have one handy in case the lighting is at a very low level. You don't want to have to worry about camera shake or not getting the model's 2nd eye in focus. You can always push the ISO, but sometimes, that's not even enough and is usually not ideal.
If the model is experienced, she may move around a lot from pose to pose, but some can be too quick, not allowing you to get off multiple shots of a good look before they strike another pose. I tend to say, "hold it" or "hold that" a lot, so I can make sure I get my shot.