I'm another one who cut it to a chin length bob. I don't think the length of it really matters for the cold cap, but when it starts falling out as an PP said there's less hair to cope with. It worked okay for me, I did lose quite a bit at the front the first time because I don't think the cap was pulled forward enough. After that, I took a scarf with me and put it over the top of my head and then wrapped it under my thighs to pull the cold cap down further! There's a really helpful Facebook group called the Paxman scalp cooling group for advice and support.
I was having three-hour paclitaxel so I did lose a fair bit of my hair, but also kept enough, when it first started falling out I used a wide head band, then I did have to get a wig, which DD said was "just like my normal hair but combed", and I wore a headband over that too for extra security. But when I was around the house, my hair was okay if I caught sight of myself in the mirror and I could go to the gym and wear a buff and pull my remaining hair out of the front. I'm glad I did it for the privacy, I didn't look like an obvious cancer patient.
I also had the straight/curly combination when it started growing back. A lot of us find the growing back stage quite difficult, but my hair returned to normal and is still quite thick.
I also got a heat pad to take with me, you may be okay if you're not having the cold cap on for such a long time, it was 4 1/2 hours for me, I didn't find it particularly painful but I did get quite cold towards the end, although that was partly because I wore ice slippers as well to stop neuropathy.
The other tip that was useful was to wear elasticated trousers, it's not particularly easy to go to the toilet whilst attached to an IV! Good luck!