indeed this is a fascinating project, involving the melding of a number of different skills
while I would agree that no 'informed' person would use a fitting, most are not so (ahem)
re the fittings:
the k factors exist, and they are not scaleable
the trick will be finding them in the sizes of interest (Imperial Eastman ??)
I am thinking 3/8 and 1/2" only; 45s, 90s, and Ts (through run and branch)
these resistances are expressed as equivalent length, so there is no way to avoid the tubing
(but at 1m in length its no biggie)
some time back I ran off the 'bent tubing' values
(who knows what thread that was ? - pHaestus, LNIKAGE plez)
for the 1m length involved, the tubing type is of no significance
re the temp effect on the pump curves, it is VERY substantial and is quite apparent at testing at even ±5°
ignore it, limit applicability to 25°C (the presumed nominal at which pump mfgrs are generating their data)
"C/W" basis is the temp differential between the CPU/die and the coolant
inlet temp; divided by the actual Watts whose measurement and calc was described
here
more later