[yyttr3]

I'm a first year college student about to take a chemistry class next semester, since I don't know anything about chemistry i've been trying to teach myself. I've been watching MIT's introductory biology, I thought it would be a gentler introduction and the actual Chem class. 
My question:
Consider a hydroxyl radical -OH, with ΔE≈1.4 which is very polar, so polar in fact that it can damage human cells. Water molecules however while still polar are not as strongly attractive I assume. In other words shouldn't the "Electronegativity" of an atom decrease once bonded to another atom. I would like to believe that the electrons in methane more equally distributed than in a C-H molecule.

So if this is true, how would you compensate for this. If true it would mean that a particular bond (Say A-B) might be polar covalent but AB4 or AB3 might have covalent bonding. So how do you figure out the new electronegativity of an atom after a bond has formed? I'm sorry if this sounds stupid, I don't really know anything about chemistry.

Sodium chloride dissolves easily in water due to the ionic bonding (ΔE≈2.1), silver chloride however wont dissolve in water. Correct me if i'm wrong but isn't this true because ΔE≈1.1 and the water molecules are not as strongly attracted to the Silver chloride. So it's easy to understand why molecules containing K or Na will always be soluble due to their low electronegativity or potentially why molecules containing Cl, Br, or I will also be generally soluble. I don't know, I just want to know if my thinking is right and if you could enlighten me in any way.

[Archer]

This is probably going to take a group effort, there are a lot of questions here. I will get the ball rolling.

Consider a hydroxyl radical -OH, with ΔE≈1.4 which is very polar, so polar in fact that it can damage human cells.

HO^- exists in completely deionised water albeit in very low concentrations (1x10^-7 mol / dm³), it must have a counter ion (positively charged species) in order to exit. In the case of pure water this counter ion is H₃O⁺. Therefore HO^- will be present in all cells. What you are probably referring to is high concentrations of HO^- being harmful to cells.