I'm not a super expert on Syms, so much of my advice is probably going to be "go ask someone else", but I'll try my best
a) Well, according to the lore, the only way for the mother to survive is if the baby is cut out prematurely, and the survival rate in that case is about 3%. I don't know whether you
have to ask permission, but it wouldn't hurt to PM Poison, the DS of Kalinor, to see what he thinks. If you were to need permission, he'd be the person to ask anyway
b) In theory, it might be possible, but you'd still need a DS or above to run the thread, and they're awfully busy so getting the attention of one is tricky. If you wanted a starting gnosis, you'd probably be better off writing up a gnosis story and submitting it to the Help Desk. (If you want feedback or brainstorming help with this route, feel free to PM me. I know it can be a bit intimidating at first
)
c) This next bit is pure speculation. I'd say if you can cover up all the traits that mark you as non-human, you might be able to pass for human. The easiest way to do this would probably be to cover everything up with clothing. Wear a scarf or hood to disguise the hair, keep the eyes shaded so the unusual color is not obvious, wear gloves and keep claws filed down, keep the creepily pale skin covered. The disproportionate limb length might be trickier, but with bulky enough clothing it could be possible to disguise. You can also use cosmetic-y type stuff to disguise skin color.
If you just want to pass as generic-human or non-Symenestra, Novice disguise seems like it would suffice. But if you wanted to get close enough to people to let them see your face and still think you're human, it would probably take a higher level of disguise.
d) I don't know of any magic that is forbidden in Kalinor. Just don't piss Viratas off I guess. Other than that, Kalinor is pretty tolerant. (Again, Poison would be the one to say for sure, but I'm pretty sure there are no limitations currently in place.)
Speaking of magic,
Morphing would be a more effective way to disguise yourself, if you're willing to deal with magic and it's many
lovely consequences.
e) As far as I know, Syms are perfectly capable of learning to ride. It's not a common passtime by any means, especially since they live in the middle of the mountains where few horses can trek easily, but I don't think it's impossible. Though, if you wanted to role-play having difficulty due to the long limbs, especially at novice levels of riding, you'd probably earn brownie points with your graders
Hope that helped! Let me know if you have any more questions/clarifications.