l never wear socks with my rock climbing shoes as l feel like it takes away from the sensitivity and grip (plus it gets hot) but my climbing partner refuses to wear her shoes without socks. So what is your preference?

Bonus Question: What have your experiences been with self-belay devices? I've been hesitant to use any but l was just wondering if you had any tips? =)

I've never worn socks with any of my rock climbing shoes. It takes a lot longer to break them in, you lose sensitivity and your feet sweat significantly more. They're made to be worn without socks. I've used 1 with setting routes and l was leery to say the least. If you use one be sure to bring a ATC or other repel device so you can repel down. l would just stick with climbing with a partner or bouldering.

First l have not used any self belay devices, l prefer to make climbing a social experience. But l do own a Gri-Gri for when those that r belaying me, r less experienced or might be a younger adult & not have as much strength or reflex that an adult has. Though, l have seen it being used as a self belay (not my idea of fun).

As for socks or no socks. l can understand ur partners reluctance to no socks. My feet get icky sweaty & the color dye from the shoes can really mess up a good pedicure. But ur right, u can not feel the rock (this really benefit really only comes after lots of experience on ur toes). Besides, if she is in board lasted shoes it is not going to make a big difference anyway.
If she is comfortable then let her climb the way she wants with what is on her feet. As time goes by & her experience grows she may transition to no socks. In the mean time, maybe suggest the light nylon bicycle socks. l wear these when the weather starts to get cooler (like now in the northeast). Plus l have martini glasses on one pair & Hello Kitty on the other depending on my mood. Just a little way to feel pretty or cool while out having fun. And remember it is all about having fun.

Hey, can not answer about self-belay devices, seeing as I've never used them. As for socks or no socks, l never wear any. l like to have as much sensitivity as possible, plus then you sweat like hell.

That would depend on what type of climbing l am doing.
If l am bouldering l would not bother wearing socks. As you said.you want the sensitivity to feel the foot holds.
If l am doing a long (all day) route then l would wear a roomy pair of climbing shoes with socks. This is due to your feet swelling on long routes. Socks keep your feet dryer.

Bonus: Nothing beats a real belayer!

The problem with wearing a thin cycling sock or a synthetic hiking liner sock is that they r slippery & she will undoubtedly have some play between her foot & the shoe. This is not good. When l have to use a sock l use a Smartwool liner sock. It is thin & not as slippery as a 100% synthetic sock. l find it grippy enough to keep the shoe from sliding & l do not lose much sensitivity.

l do not use self-belaying devices. That is what ATCs & partners r for.

l hate socks!

Its a climber is preference on the socks/no socks question. No point in having a distraction while u r climbing. For her, not wearing sock could be such a distraction that she doesnt pay attention to what is going on during the climb.
As for our self-belay question: for what purpose? l use a gri-gri when l set routes at the gym. However, l always break properly before putting my weight onto the device. (If u dont & u go to slow, then the gri-gri may not break. If u go to fast, then the gri-gri can bounce & release itself. For all other climbing situations, l use a belayer. No point in risking it.