... Great questions! In my experience, it can take up to a couple of hours to fully absorb into the skin. If you are applying a thin layer, it may take even less. It always seems to me that the further I am into the treatment process and the more dry my skin becomes, the faster the cream absorbs.
As far as sleeping, I wear an old t-shirt and try to apply the cream an hour or so before I lie down to allow it plenty of time to absorb. If I feel that I have transferred some to my pillowcase or sheets, I do a quick change of bedding before the next night.
I have used Efudex on my chest, back, and face fairly regularly for several years now, and I haven't encountered any big issues with transferrring cream to bedding, clothing, or other parts of the body. My advice to you is to take things one day at a time, follow your doctor's instructions for applying it, and allow yourself plenty of time to let it absorb. You will soon find yourself in a routine that works for you.
I am including a couple of articles that may help as you move forward.
https://skincancer.net/life-with-skin-cancer/tips-for-efudex-users
https://skincancer.net/life-with-skin-cancer/how-use-efudex
Please know we are here for you and will gladly answer any questions that may arise as you treat. Hang in there! April, SkinCancer.net, Moderator