Map of Flash memory ??

0x080002800 is a typo - it should be 0x08002800 as it suggests on the line above.

Yes, the new binary is much smaller. I accidentally left the optimisation switched to size when compiling 1v67 - but it shouldn't be a big problem. The binary in the zip contains the bootloader (which is 10240 bytes) - which explains your discrepancy.

It turns out that test is broken :( Since the switch to 32 bit, 0xFFFFFFFF is interpreted as a signed int, so it's now -1. Try this and you'll have more success:

function isPageSafe(addr) {
  for (var i=addr;i<addr+2048;i+=4)
    if (peek32(i)!=-1) return false;
  return true;
}

I'll update the docs.