Q - 1. Normally you have to set hardware-condition (PSEN=0,EA=1,ALE=1) to run the bootloader but my old hardware doesn't support this (not necessary for T87..). Is it possible to run the bootloader (and flash the uC) in the sw-application? (for example setting the PC on FC00h?!?)

The normal operation is to run the bootloader until the chip has been programmed - then you can jump to fc00 in software, IF you restore the SFRs to RESET values.