Is delay1() actually 1us?
Yes.
Also I've read in the forums/code a quite a few differences about the timings for the bus, is there a up to date list of times for StartBit, 1, 0, and ACK?
I set timings by experimental. Found low and high times wich works on my HU and set average.
I'm also looking at using the internal comparator in the ATMega88 instead of the LM339, is this possible?
It is possible i think.