a) Could be the card or the adaptor. Contact firstname.lastname@example.org to get them replaced.
b) Unclear how the H8000 could know the DAW's tempo apart from MIDIclock. Mind reading ? Note that not all delays are tempo-controlled – depends on the preset.
c) Not sure what your levels problem is – normally you set everything to 0 dB and the outputs are about the same levels as the inputs. You don't say what your routings, sources and destinations are, so it's hard to suggest anything. Start by getting a good level on the meters, then adjust the outputs for the desired level.
d) Not all ADAT cables fit well into the TosLink connectors. Some are better than others – there have been a number of forum post on this topic.