sorry, here is the message i would send:

->1. Small progs are very fast written to the flash. The short time could be ok.

->2. if you have no delays in your programm, the led blink very fast. you don't see it.

->3. what programming tool do you use? before you program the at89s8252 erase the flash and verify the stored data.

->4. the bits are set by the programmer. you can find the description of these bits in the datasheet (www.atmel.com).