How to delay the transistor turning on using a photoresistor?
A 2n2222 would provide a higher collector current - one example at http://www.fairchildsemi.com/datasheets/PN/PN2222A.pdf

But, in order to give you a sharp transition you'll either need more stages or to switch to FET.

Perusing the datasheet, it looked like you probably want it to be all the way on for an R of about 2 kOhm and all the way off for an R of about 20 kOhm.    In order for it to be off at 2 kOhm, you'd need about 50 kOhm instead of 1 kOhm in the upper resistor.  However, when it is on (say at 20 kOhm), the 50 kOhm will limit your base current to about 200 microA.  Assuming a beta of 100, that only gives you about 20 mA of load current.