You need about 50ml per sheet of 4X5 of C-41 developer, for the 2550 you will need a min of 640ml of liquid in the drum when processing 12 sheets which is just over 50ml.
C41 is a very forgiving system. While the system calls for very exact temp control, and continuous agitation, you can manage just fine without either of those things, though like i said above - you will have a hard time matching results or keeping any type of consistency without a proper, mechanical system that regulates temp/agitation.
The simplest method is to use a sink/bucket filled with water at needed temp. for the 3:15 minutes of dev time, the temp shift is meaningless (dev cna shift +/-3 degrees and stay within tolerance)
You will agitate with the tank floating in the water, or agitate with short breaks to submerge the tank and help maintain the temp.
There is never a need to pre wash c41, blix temps can be off +/- 10 degrees and stay within tolerance, stab (or wetting agent) does not need to be tempered in any way.
You should check out our C41 (still out of stock at the moment), and contact me directly, and i can send you the manual for the kit which should answer many questions for you.
If you do get serious with C41, and i hope you will (such an easy and fun process... ), you will eventually want to get a processor with a lift to make life easy.