I wrote to Real Doll with some questions. Here are their answers:
Do the pair of feet have fused toes, or are they separate? The big toe is separate but the other toes are fused.
Do the feet have an internal skeleton? No, the feet are made of solid silicone.
Do the soles of the feet have a realistic skin texture? They are as textured as the persons we molded them from

FYI, the Real Doll feet do NOT come with shoes. They also state:
Medium skin tone with either red or french toenail polish in either sizes 7 or 8 are $149 per pair. All other skin tone and nail color options are $199 per pair.
The
other manufacturer's* feet come with a pair of shoes, but you don't seem to be able to pick which shoes. Like the Real Doll feet, the big toe is separate but the other toes are fused.
I did find another product called Belladonna's Foot Soldiers. They're around $50, but are made of rubber and the reviews of it say that they stink. So, I'll pass on those.
* Edited because of this, AlexKnight: viewtopic.php?f=8&t=38015