Need help with some theory concepts

[npoturnak]

Hello,

I'm writing to this forum because still have a question I wanted to aks long time ago. I thought it would become clear to me once I get more practice with questions, however, it didn't help.

My question is really about modifiers.

1. Do I understant this correct that if we have a modifier starting with "which", "that", "who" then it modifies the word that immediately preceeds it? That means the GMAT rule is to place the modifier as close to the noun as possible.

ex. I'm the person, who really loves fun.
Use the book that is on the second shelf.

The question: Is it correct that this types of modifiers are used only to modify nouns?

2. This is the part which seems more complicated to me. Let's consider the following examples:

ex. the number of students increased doubling the number of students in previous year

ex. a cannon shooting dead chickens at airplanes has proved helpful to demonstrate what kind of damage can result when jets fly into a flock of large birds.

The question: If we have a modifier in "ing" form how do we need to use it? Are we allowed to use these modifiers with nouns or only to modify clause/action/verb?
Sometimes when I encounter such modifier it is unclear what it modifies: the noun it touches or the verb or the clause itself. Please help to understand how to differentiate. Do we need to use commas separating such modifiers?


One more example: A recent study of ancient clay deposits has provided new evidence supporting the theory...

Is this a study that provided and supports? ("supporting the theory" modifies the whole clause?)
OR this is the "evidence" that is modied? (evidence is supporting)
So when I have this kind of example how do I need to choose?

If you can provide links to additional information that would be much appreciated.