Hey @Sister.
Yes it will thin. It keeps its normal shedding routine plus more, and of course, for the moment it isn't growing back. As mine thinned evenly all over, I was the only one who could spot the difference. I didn't really follow the rules and washed my hair quickly from mid length (can't fall out from the middle right?) down every day because it was about 35 degrees most of last summer and the thought of only washing it once a week didn't impress me at all..
I found the cold was not really a problem after the first time as you know what to expect.
The nurses can time the premeds with the pre cooling as you wait time there anyway. And the after cooling can start as soon as the actual chemo infusion is complete. So once the last bag of fluids ran through I was only there for an extra hour with the AC and 45 mins for the taxol.
Check on the cap every so often through treatment and make sure it is still snug on your scalp. I used to push mine down a bit about every 15 mins (yes, I was slightly paranoid). It's all in the fit and rechecking throughout the treatment. I have been in close contact with the nurses at my cancer care centre and they are having excellent results now they are pros at using them. Around 75-80% success rate.
You can push your hair back away from your face. As long as your hair line is covered with the cap and it fits well on your scalp.. I put a hair band around mine so it sat just under the front of the cap, stops freezing your forehead off and controls your hair.
Halfway through Paclitaxel my hair started to grow again. So it is now 8 months since I finished chemo, the bits that shed out are about 7 inches long and have come back with a curl on the end so it's a bit interesting taming it down some days. Kind on look a bit like a Chinese chicken when I get up It's thick and healthy and the same as it always was.
I'd be happy to send you some before, during and after photos if you would like. Just send me a pm if you want any more info.