(SC) Waitting for your HELPS!-Please

hello every super NNs, I am a newbie and need your helps desperately

I have 3 questions and would like to have your opinion about them:

1) " first of all " should followed by "secondly" or "second"

  2)   A recent study has found that within the past few years, many doctors had elected early retirement rather than face the threats of lawsuits and the rising costs of malpractice insurance. (I don't think E is right either,since it has given the tense " within the past few years", should "had" instead of "have" be used?????)

(A) had elected early retirement rather than face

(B) had elected early retirement instead of facing

(C) have elected retiring early instead of facing

(D) have elected to retire early rather than facing（E）

(E) have elected to retire early rather than face

3)how do you understand the meaning of the following two sentences: why we can not break down the sentence in 1) stytle

1) the theory of global forests fires ignited by a meteorite impact that contributed to the extinction ......

2) the theory that global forest fires ignited by a meteorite impact contributed to the extinction

Thank you!!!!!!!!!!!!!!!!!!

1）second = secondly = first of all = firstly 当它们都作sentence adv.时

可参考大全23题

断句无错，但两句话的意思和重心不同。

thank y zenger, much appreciated, I have to remember "within the pass few years" require prepsent perfect (note to myself!!!)

also,I find sometimes when i am in a hurry, I tend to confuse the main point in a sentence. (must be careful...)