The 350Z seems to have a fairly decent brake set up as standard, those Brembo callipers feel strong and the disks are reasonably generous in their diameter and vent width. So for me, the first key to brake longevity is decent fluid, then decent pads. I think that would offer better performance than regular fluid, pads and good disks.
That said, I will need disks as mine are reasonably worn. Have you more info on the DBA disks - are they a blueprint of the oem disk or are they better quality? I see the 4,000 series slotted and drilled disks on your website, are these suitable for the odd trackday?
Any recommendations on pads?
You are correct in saying that high performance fluid and the right pad for application will make a big improvement. It really depends how hard you are on the brakes on track and indeed what track you use the car on. Somewhere like Knockhill for instance is extremely hard on brakes and my Skyline really struggles there compared to the Nurburgring where the set up I ran coped perfectly well.
The DBA discs run a unique Kangaroo Paw venting system, it sounds like a gimmick but the way it allows the heat to disperse makes a big difference to running temperature. Selecting the correct pads though is crucial to operating temperatures, DS2500 is a very popular choice for a lot of guys using the car on track but there are better options available depending on your driving style and needs. Ds3000 or Pagid RS29 would be a consideration as would Carbon Loraine RC6. We would only recommend the DBA T3 Slotted for track use, a drilled disc is not a good idea for hard use unless the holes are cast into the discs like the ones you'll find on a Porsche.
To give you an example I have a customer with a Z4 M who used DBA 4000 Slotted with DS2500 round Knockhill, this guy is a very aggressive driver and he managed to crack one of the discs, this was down the the DS2500 simply not coping with the very high temperatures the brakes were getting to, we switched him to DS3000 and he never had the problem again.