If you only want to remove the mouseover change from the power text, then only make the above change in the section of the code that is related to the power text. It should be pretty obvious -- that section of the code is inside a function with "Power" in the name, beneath a comment block that says "Power", and calls lots of functions with "Power" in their name.
Even if you're unfamiliar with programming, instead of just going "omg code I don't get it, halp!" slow down and try to read it. Lua is a very easy language. It's basically giving instructions to the computer in plain English. And, if you break something, just undo your last change and try again. You're not going to make your computer explode or cause the sun to collapse into a black hole by raising a Lua error in WoW. It's okay to make mistakes -- that's how you learn.
As for the health text, find the PostUpdateHealth function (in Functions.lua, as the name might imply), go to the end of the function, and make the following change:
Code:
elseif bar.__owner.isMouseOver or unit == "target" then
bar.value:SetFormattedText("|cff%02x%02x%02x%s|r", color[1] * 255, color[2] * 255, color[3] * 255, si(UnitHealthMax(unit)))
else
bar.value:SetText(nil)
end
end