No, not in less you join the college of winterhold but like the companions you just use whatever you like and with the dark brotherhood you don't need to but if you would like to use the illusion spells it would help a lot but you don't need to and if you are going to be a thief use illusion spell and go to the whispering door and do its quest so you can get the ebony sword i think its the most power full sword but you have to be lvl 30 to get it
Go over to your magic menu and go down to powers, it should be there
as long as you have 2gb of ram, which is how much Bethesda have restricted Skyrim to use on any computer ( without the use of a mod), you should be able to run Skyrim, mediocrely
wood elf is what I would go for They are the best archer class in the game and all elfs are good at magic and a wood elf is also good with sneak You could also go with the cat race They are the best thief like class and are good arcary
skyrim
Use a Khajiit, they are good at sneaking.
You 'use' RAM, not lose it.
Get the conjure familiar spell and use it
No. Sunlight boils a vampires blood preventing your health and stamina from regenerating. It will regenerate if you are in a dark place or at night. I personally am arch mage and my robs regenerate my magic 100% faster, so I just use my magic to regenerate health, and have a perk so that it also restores stamina.
Equip arrows and then use poison.
Yes, all playable races can use shields.
If you have Hearthfire installed you can use them to make Flour from Wheat.
Dark Elf, Khajit or Argonian