The most defining characteristic of Mr Magoo was his eyesight. He had terrible eyesight and kept mistaking one thing for another.
The writer in this case is suggesting that conservatives in the media can't see the world for what it really is.
The meaning of "spring in one's step", as Manny used it, is this:
Wiktionary
spring in one's step (idiomatic)
enthusiasm, energy or a positive outlook or cheerful attitude.
After her promotion, she carried out her new position with a spring in her step and a contagious smile.
The meaning of "spring" is "jump" or "leap". Someone who has a spring in his step is the opposite of someone who is depressed.
However, Jay has interpreted "spring in my step" to mean that Manny's peers have told him he has a spring in his step because they think he is effeminate, or even homosexual. Manny didn't mean it that way at all, and "spring in my step" is his own phrase, used to mean that he is light-hearted because of his infatuation with a girl. The joke is Jay's misinterpretation, contrasted with Manny's unconcern.
Compare "light in the loafers":
Grammarphobia
Cassell’s Dictionary of Slang (2d ed.) has only a brief entry, describing the expression as ‘50s American slang and adding that “the image is the stereotyped effeminate male, tripping along.”
The Random House Historical Dictionary of American Slang, which defines it as effeminate or homosexual, lists a series of references for the expression dating from 1967 to 1996.
Best Answer
This is more of an informal way of speaking. To "burst" implies (in this context) :
This simply means that the speaker is super proud of his hardworking girlfriend and his feeling of pride towards her is very high, and for the same he has used "burst" to describe the level of pride he has towards her. This feeling fills him up and he feels like he may explode (metaphorically, of course).
"To marry the sh*t out of her..." simply means to marry her and keep her very happy. This is a common usage, especially in American English. Similar sentences would be:
This is just to create an emphatic impact. There is specific meaning and sh*t has got nothing to do with the actual concept.
Another usage is to replace 'sh*t' with 'hell' or 'bejesus' :
This simply means : 'to make one feel extremely frightened'.
These are highly informal and never to be used formally. It may come off as very rude or offensive to many people.
NOTE: 'scare the sh*t out of someone' is commonly used. 'Marry the sh*t out of her' is an analogy to the same, but isn't used widely (it is content-specific). There are many ways you can recreate it, based on the context.