1. and 2. are not an issue, FPC can build already for ram-less AVRs like the ATtiny28, smaller is basically not possible
:
ppcavr empty -Wpattiny28 -Cpavr25 -vi -O4
Target OS: Embedded
Compiling empty.pp
Assembling program
Linking empty
2 lines compiled, 0.1 sec, 42 bytes code, 0 bytes data
The 42 bytes are mainly overhead for interrupt vector handling.
3. is a small issue, but there are normally enough tools out there already.