Sentence Correction

Hi
I have loads of questions on modifiers. I have seen your "Thursdays with Ron" which is very useful and read few Posts on modifiers and have a couple of questions as below. Please help me with the questions i had about the role of modifiers and especially the essential vs non essential noun modifiers

Question 1
 After decreasing steadily in the mid-1990's, the percentage of students in the United States finishing high school or having earned equivalency diplomas increased in the last three years of the decade, up to 86.5 percent in 2000 from 85.9 percent in 1999 and 84.8 percent in 1998.

(A) finishing high school or having earned equivalency diplomas increased in the last three years of the decade, up to 86.5 percent in 2000 from 85.9 percent in 1999 and
(B) finishing high school or earning equivalency diplomas, increasing in the last three years of the decade, rising to 86.5 percent in 2000 from 85.9 percent in 1999 and from
(C) having finished high school or earning an equivalency diploma increased in the last three years of the decade, and rose to 86.5 percent in 2000 from 85.9 percent in 1999 and from
(D) who either finished high school or they earned an equivalency diploma, increasing in the last three years of the decade, rose to 86.5 percent in 2000 from 85.9 percent in 1999 and
(E) who finished high school or earned equivalency diplomas increased in the last three years of the decade, to 86.5 percent in 2000 from 85.9 percent in 1999 and
If I had a choice same as E except that a COMMA before 'who' will WHO refer to immediate preceding noun that is United States , why can't it refer to percentage of students in United States is it because who is non- restrictive and by referring to percentage of students in United States it will act as restrictive

Question 2:

Can Non-essential modifiers modify the near noun or the entire noun phrase or noun + noun modifier depending on what makes sense or it can only refer to the nearest eligible noun where as essential modifiers can refer to entire noun phrase or noun + noun modifier. When i say eligible does it mean both grammar and context

Question 3
Can we apply the below rules to find the correct modifier
 First check if the modifier makes grammatical sense with what it's modifying as in sub verb agreement, singular plural, whether the pronoun that's supposed to refer to people is instead referring to things etc.
 Check if the meaning makes sense from the context of the sentence. Some sentences there is not enough context available to make this distinction in other words both the nouns make sense as per context that's when it becomes ambiguous

Question 4
Parents of young children, who often need to take time off work unexpectedly, benefit considerably from flex-time policies.
As per context and grammar it's clear that who refers to parents so I will say that this sentence is correct. However if I think COMMA+WHO is a non-essential modifier so will it modify the entire phrase or only noun parent

Question 5
I am going to the show with my friend Kevin, who likes Elvis, the nicest person I know
Can I say that the above sentence is correct because I can scoop out 'who like Elvis' because that's the non-essential bit and can say its correct 'the nicest person I know' is referring to 'Kevin'

Can I say that the above sentence is correct because I can scoop out 'who like Elvis' because that's the non-essential bit and can say its correct 'the nicest person I know' is referring to 'Kevin'

Can i scoop out/eliminate the non essential modifier 'who like Elvis' just as i do for sub verb agreement questions i remove the modifiers within comma. Can i do the same in such questions as well when i need to find which modifier modifies which noun

Question 6
The box of nails, which is on the counter, is to be used on this project.
From the verb is we know that which here refers to the box and not nails but again which here is nonessential but by modifying box isn't it used as a restrictive clause which shouldn't be the case.
Even if it was box of nail according to me it would still refer to the entire phrase box of nail because the nail is contained in the box and we can't say nail which is on the counter

Question 7
The Roman Empire expanded to most of southern Europe and the Mediterranean region by beginning of the first century C.E., bringing the Latin language with it, from which were derived Romance languages, including Spanish, French, and Italian.

a- the Latin language with it, from which were derived Romance
b- the Latin language with it, and from which deriving Romance
c- with it the Latin language, from which derive Romance
d- with it the Latin language, from which derives Romance
e- with it the Latin language, and deriving from it the Romance
First Question
In answer choice A why can't from which refer to Latin language. I have seen some constructions in which the non-essential modifier refers to the far away noun based on the context. As per the context from which will refer to Latin Language and not Roman empire or it
Second Question
Can we scoop out this portion",bringing the Latin language with it, since its enclosed by comma on both sides and say that from which refers to Roman empire which is wrong. Can we scoop out such nonessential modifiers when we are trying to understand what the modifier is modifying just as we do in subject verb agreement?

Question 8
Do all non-essential modifers like WHICH has to refer to preceding noun or only eligible preceding noun or noun phrase. When we say eligible does it mean eligible based on grammar or context?

I am sure your questions will draw more attention if you post them separately and with proper formatting.