1. Not correct 2. Correct 3. Black holes will not be so intimidating when we understand them. (Implies that we will understand someday, and then they will not be so intimidating.)

Yes, an OB-Gyn is an obstetrician/gynecologist. This is a doctor who primarily treats pregnant women and delivers babies. From the context, I would guess that the woman on the stretcher was the wife of Lyndon Johnson (US President from 1963-1969.) Her face was covered to protect her privacy from photographers, probably because she was suffering a miscarriage (death of a fetus). You asked about the stretcher and the corridor. This simply means that she went to go get a stretcher, as requested, and then took it back to the hallway where the policemen were waiting with the patient. A stretcher is a kind of small cot/bed on wheels, used for transporting a patient within a hospital. A corridor is a hallway. That's my best guess anyway. A bit more context might help, if you could provide more of the paragraph before the excerpt that is here.

1. ask a number of people to see if anyone has an answer, or to collect a variety of opinions from which to choose. 2. A. stop working, in the sense of a vehicle. (e.g. My car breaks down every month. The bus broke down.) The vehicle may be reparable, or not, but 'to break down' does not imply that the vehicle is permanently disabled (broken). B. have an emotional collapse. This is often hyperbolic (meaning: describing an exaggerated statement). (e.g. My friend broke down in the coffee shop when she saw her ex-boyfriend with his new girlfriend.) 3. visit. (e.g. I'm going to call on some friends after church on Sunday.) 4. contribute financially. (e.g. Everyone please chip in to help pay for the dinner bill!) 5. become ill. (e.g. I come down with the flu every winter.) 6. cut in. When a man interrupts a couple who is dancing, to request to dance with the woman. (e.g. "Excuse me sir, may I cut in?" Mostly seen in old movies.) 7. The correct term is 'to get around to.' It means to do something eventually, often a chore. (e.g. One of these days, I'll get around to cleaning out my attic.) 8. disappoint someone / yourself. (e.g. My husband really let me down when he forgot our twentieth anniversary.) 9. disassemble. I need to take apart this furniture so that I can put it in storage. 10. resemble, as in a parent or other relative. This resemblance can be physical or behavioral. (e.g. "My son really takes after his grandfather. He looks just like the pictures in the family album!" "My daughter takes after my sister. They both throw temper tantrums.")

Las anotaciones azules: O no hay una manera buena traducirlo, o no sé qué significa. 

A short fragment from " El Amor En Los Tiempos Del Colera " by Gabriel Garcia Marquez.

"Do You want stay alone?" " He asked."
Then, he extended his frozen fingers searching in a blind way the dark, searching by touch for the other hand, and found it waiting for him. Both of them were so much lucid enough to realize, in a itself that fleeting instant, that neither of the hands were the one that they was as either had imagined prior to feeling its touch before themselves touch each other, but rather two hands of old bones. But in the next instant they are yet. She started to talk about her dead husband, in the present tense, as if he were alive, and Florentino Ariza learned knew in that moment that for her as well, was the time had arrived for her to be she asking herself with dignity, with courage greatness, with the irrepressible desires for to live, living, what have to do with the love remained that she had guarded without owner.  <----- Although this is the literal translation, I think you want something more like, "... guarded for the husband for the husband that had left her." Unfortunately, this is much less poetic. 

- She went to Spain even though her doctor had told her to rest. - Although her doctor had told her to rest, she went to Spain. - Despite her doctor telling her to rest, she went to Spain. - Her doctor told her to rest. However, she went to Spain anyway. - Regardless of the fact that her doctor had told her to rest, she went to Spain.

Technically, your sentence was mostly grammatically correct, but it was a bit awkward. If I were you, I would change it to the following: "The company has designed and installed a high quality security system without any negative impact on the budget."

Depending on the situation, they basically mean the same thing, except that you would not use them the same way. For example, you could say either, "I have two reasons," or "My reasons are twofold." You cannot swap them. Twofold also means doubled, although I'm not sure that makes it any clearer. There is a similar word. "manifold," which is similar to "twofold" except that it means "many." For example, you could say, "I have many reasons," or "My reasons are manifold." You would not use twofold or manifold with physical objects. For example, you would not say, "My shoes are twofold," or "The flowers in my garden are manifold." These words are fairly formal and not generally used in casual conversation.