If you get a 5L kit, liquid, then all the elaborate calculations above are not needed.
Use Developer as one shot, straight, mixed as per instructions in the box, at minimum stated of Jobo tanks (or any other you will use, though Jobo's are pretty economical), and you will still achieve the max capacity of the developer (if running 6 sheets at least per run).
I am not sure what the results of using the ciba tanks are, but i know many folks use them and are happy, that is not say the results are "good" or meet any kind of specific guideline.
C-41 is usually *** processed at 38.4C, which is about 101F, and to make things easier most manufacturers will mark at 100F or 38C. Dev time is 3:15, for starting point at that temp.
Even if you will still have some dev capacity left, its worth that little bit of "waste" to make sure you have the same perfect results time and time again. One shooting the Dev is the way to do just that. Bleach Fix or Blix can be re used with no ill effects, and you can always re blix as needed if its dead, but even then, with any kit you buy, you will have X3 the amount of blix material compared to the amount of dev you have, even if used to exhaustion.