Yes normal wolves exist in Westeros. I could include a plethora of quotes but for an idea of how many times wolves are mentioned see these queries on A Search of Ice and Fire for wolf (516 results though this includes false positives like the Hour of the Wolf) and wolves (324 results). Of course not all refer to wolves but most seem to, see an example quote ...
It was Drogo, Rhaego and Miri Maaz Dur.
“They are mine,” she said fiercely. They had been born from her
faith and her need, given life by the deaths of her husband and unborn
son and the maegi Mirri Maz Duur. Dany had walked into the flames as
they came forth, and they had drunk milk from her swollen breasts. “No
man will take them from me while I live.”...
The Sack of King's Landing takes place in 283 AC, taken from the Appendix in A Dance with Dragons:
In the 283rd year after Aegon's Conquest, Robert of House Baratheon, Lord of Storm's End, overthrew the Mad King, Aerys II Targaryen, to win the Iron Throne. His claim to the crown derived from his grandmother, a daughter of King Aegon V Targaryen, though ...
The defense of the Wall is the duty of the Night's Watch. It is not the duty of the Warden of the North.
Night's Watch can ask for men if needed, which actually happens (in S05E04):
(Sam) Lord Ashford. Lady Caulfield. Lord Smallwood.
(Jon) I've never even heard of these people.
They haven't heard of you, either. But we need men, and they have some.