There's a ton of information on the forum here about C-41 in general, as well as Tetenal, so you'll definitely want to spend some time searching first.
Based on quite a bit of research I've done myself in the last few weeks, I've come to the conclusion that, at least for a hobbyist living outside of Europe, Kodak is quite a bit of a stretch to do economically. Fuji makes a kit, but is only realistically available in Europe (import shipping to the U.S. was at least 50 _pounds_, roughly $80, not counting the cost of the kit itself). So... I went and bought the Tetenal 5L kit from B&H, which should be arriving today.
From what I've gathered, the Tetenal kit uses a blix, which may or may not produce as good results as Kodak or Fuji bleach + fixer combos. I use the Kodak E-6 kit at home, and get great results, and have a local lab who processes C-41 on a minilab, so I have some basis to compare with when I try the Tetenal, and will try to report back. But one thing I did learn from another thread is that, most likely, the two liquid components of the blix, which are separate in the Tetenal kit, are not, literally, bleach and fixer. But combined, they form blix... so, it is most likely not feasible to derive a bleach & fixer combo with any of the Tet kits.
As for temp control, it seems that in C-41 it is even more critical - the tolerances are certainly tighter, by the book, than E-6. But, the film develops faster, so you only need to control the temp for about half the time. You're going down the right road by using some sort of heating element... I use a Jobo CPE-2 Plus, and get reproducible results every time with E-6, so that's one large part of the equation that I don't need to worry about when I try the C-41.
Even without a heater tho, as long as you can reproduce a developing time that averages out to the target temp, I believe you will get the same results - i.e., the temp swings themselves won't kill the film, but ending up with an average result that is out of bounds will (to a degree - of course - this is all analog after all!)
As a hobbyist, I approach this as something that is fun to do - when it becomes un-fun, then I've gone too far... so try to have fun with all this, and remember, a large part of this is art rather than science.