Quick answer yes
only problem the front end drivers ie. the exe files to program the piv32 & debug, The sample files are not down loadable from Microchip site, only manuals & data sheets(pdf) no soruce zip files
1. U1. a 4550 is a ICSP like a pickit2 you could read the chip via J3. (can't see Microchip protecting code)Front end will allow update and replacement of a corrupt bootloader.
2. to program the pic32 RC0 puts it in program mode.
3. RB0 & RB1 supply Data & Clock
you would need the data sheet for the pic32 to see how a bootloader is used.
I think most people would just use a sample board.
i have got a sample board but the reason that i want to build my own is :
i have no connector or board for expansion connector , and i cant use rs232 , adc , dac , .... . i can just load the game and see the leds blink!