I had a nerdy thought this morning too... about ketosis and IFing.
When I fast for say... 24 hours... I wonder how much fat is lost.
I'm not a ton of help with your questions. Not sure how long it took me to get into ketosis the first time through. It was too long ago to remember. Ketosis happens on and off, though I'm USUALLY "on." My carbs are generally under 50g, though lately they've been higher with all the winter squash and root veggies.
Yes, Keto-stix are available OTC. You can pick them up in the diabetic supplies, or ask the pharmacist where to get them. I keep a jar in the medicine cabinet.