I've been doing this on various forums for the cars I've sold and owned for years now. If you think this is the first (or last) time I'll get flamed, you've got something else coming. I guess it's half the fun- right slow04wrx?:P

if it were me, I'd run those tires through to next winter (they'll be BALD though come fall), put snows on the stockers for winter, and buy a new set of rims/tires in the spring. If you're not in a climate that dictates snow tires, then, yes, 5-10K is a pretty reasonable estimate.
As far as brakes, it really depends on how hard you use 'em. could be 5,000, could be 15,000. But I'm always on the cautious side with pads, because if you wear them too low, and mess up the rotors, you go from a $150 brake job to a $700 brake job (using rough figures so please don't flame for estimation) .

Enjoy your new subie and welcome to the forum!