Choosing fingerless gloves was a good idea... although I'd imagine the gloves would need some sort of rubber or a non-slippery yarn for the palms... hmm. That's all I got.
On the wrist warmer vs fingerless gloves subject: I usually think of wrist warmers as just a band that goes around your wrist, like a really wide bracelet. Although, some people call those pulse warmers.
I've seen patterns called wrist warmers that are made the way you mentioned... just a hole for the thumb. I usually refer to those as fingerless gloves.
I've also seen gloves where you knit about an inch on each finger, but, they're also called fingerless gloves. Hmmm. I guess technically they should be called 1/4-finger gloves.
Oh, the odd world of knitting.