Water - Max=90oC / Min=70oC
Oil (Shell Helxi Ultra, on intake side of engine) - Max=115oC / Min = 65oC
Pressures (guessed from watching (carefully!) max/min on fast road driving):
Oil - Max=70lb/in2(5bar) / Min=50lb/in2(3.5bar)
Fuel - Max=50lb/in2(3.5bar) / Min=30lb/in2(2bar)
Glad you have got them all fitted. OK, my opinion on what to set the alarms at are as follows. I am sure everyone will have a differing opinion, but if everyone explains why, then you will be able to make your own mind up.
Water Temp: The SPA only gives alarm on the max temp. I would go for 90 deg. I say 90, because your car would never normally see 90, so if it does see 90 for some reason, then something could be wrong, and it gives you time to ease off and do a cool down lap.
Oil Temp: Again it will only alarm on max value. I would set it at 100. I would do this because mine doesn’t see 100, so if it does then for the same reasons as above I would want to ease off. I don’t know what Oil temps you are seeing, mind you I guess you don’t either if this is the first time you have had a gauge. But if your car is anything like mine with the original oil cooler setup, expect to see WELL over 120 after a 15 minute track session.
Oil Pressure: The SPA alarms on only low pressure and I would have it set to 3 bar. Now, this may annoy you, as at tick over especially when warm the oil pressure will normally fall below this figure. However as you said, these alarms are for when you are flying round the track with the red mist down and as your oil presure at full hammer will be well over 4 bar, if it suddenly drops below 3 bar, you want to know ASAP so that you can ease off, as it may be hitting 3 bar on its way down to ZERO bar. If you can catch it at 3 bar and ease off then it could save your engine. This scenario is usual on long corners where your oil pickup pipe gets starved.
Fuel pressure: Again it alarms on the low figure. I am guessing you are still running 3 bar fuel pressure and as such it should never really move from 3 bar. It will fluctuate a little bit for the odd nano second which isn’t a problem, but it should stay around 3. I would set it to 2.5 bar. You may get the odd alarm every now and then for a nano second, but if your fuel pressure drops for a sustained period your engine WILL run lean and MAY melt. Again fuel surge in long left hand bends (the pump is on the left of the car) may leave the fuel pickup gasping for fuel.
Hope this helps.