Faraaidh and Sunnats of ghusal

Spending lengthy periods of time in the shower

Q: I have a urine leak problem. So after I shower I wipe dry then wash close to the slit so that I can be as pure as possible and then dry that water up. At times the water flows away without leaving a bead of water left over and sometimes it leaves a bead.

Now I fear that if that bead of water moves it will go on a part of impurity on my private part, all the water on my private part in some way or the other is connected to each other due to lines/wrinkles on the skin. 

Does it now make the whole private part impure? What would be an easy way in making istinja or even coming out of the shower? 

Sometimes in attempt to get the water to flow off immediately I spend 45 mins plus in the bathroom.

Fardh ghusal for a person who has a medical device taped to his skin

Q: There is a device on the market which is attached to the skin. It gives you a continuous and real time reading of your blood sugar levels by which a diabetes patient will know when to take his insulin and how much insulin he should take. (Not over or under administering the medication) 

The device is quite expensive (removing & changing the device each time you require a farz ghusal will be very costly). The device has an adhesive tape by which it is attached to the skin thus preventing water from reaching underneath it. Will the farz ghusal of a person wearing such a device be valid if he makes masah only over the device and washes the rest of the body?

Doubts regarding ghusl

Q: I have issues with my ghusl concerning the validity of it due to specific barriers. 

I scrub my ears yet there is still some sort of wax at the part that curves. I sometimes scrub so hard it scabs. 

I also have some white patches in the middle of my chest. I’m not sure what it is but I also need to scrub hard for it to be removed. 

I have an ear piercing hole, how do I clean inside of it, if it’s closed but sometimes some sort of sebum comes out when I rub my piercing hole which is pretty much shut. I have some hard dirt on/in my bellybutton. It is extremely hard to remove as it’s engraved in the grooves of my skin.

Lastly I have an eye issue called blepharitis where dandruff like flakes are on my eyelash and eyelid. Sometimes I finish my ghusl and see these flakes/crust on my eyelid and lash. Are the things mentioned barriers for my ghusl?