Wow, a Z-80 project today.

Rodney Zaks' book was the bible on the Z-80.
Mine became very dog eared as I read it on the train many times going to/from RMIT.
I even have a Microprofessor I was given many years after I had finished RMIT, we used these at uni at the time and they had a nice fluorescent 14 segment display.
Never been fired up though by myself!
And yeah the Z-80 sets the program counter to 0000 upon reset and starts reading opcodes from there.
Other processors used vector tables and other techniques, but a simple lets start reading from 0 was the Z-80's approach.
One unique feature the Z-80 had at the time was shadow registers to avoid wasting time doing context switches in interrupts, very handy.