regarding I2C:

Hardware supported (which is the only possibilty at the slave) I2C is a pain - all states must be handled correctly else I2C will stall.
This means testing & debugging each step on master and slave (which is a lot of work because I have only 1 pickit).

Today I have finished the I2C code, seems to work now very well and without race conditions - fixed them today.
For tomorrow a test with 3 slave pics (currently only 1 during development) is planned.
If everything works - I will send the code to bkkcoins.