well it depends.....Manual Focus 35mm beats every lens for portrait photography, Af wont even come close to it
basically depends what do you capture mostly ....nature, portraits, macros, night ...
if you want an all purpose lens in easy budget then go for 18-105 which also comes with Nikon D90
if you can extend your budget then go for 18-300 sort of all purpose lens..which also does macro to an extent
while IS as someone mentioned is Image Stabilization and copyrights by Canon ..i mean there is nothing like preference of IR
it depends which lens are you gonna buy....Canon has IS, Nikon has VR/VRII, Temron i suppose calls VC (Vibration Compensation) ...and trust me you wont find that much of a difference in any of the above.
Since poster asked for Canon then he can only have IS..although you can put a converter and use any other lens as preferred
while going close, you normally turn off VR/IS/OC for a cleaner photo provided you have steady hands and even if not, it wont help you much there