“When I listened to music in my university dorm, I used to wear (headphones) so that I (would) not interfere (with my) other roommates. It was considered rude to play music out (loud).”

I called the apartment manager. (More often, I think we'd refer to that as "the management company" or "the property manager.") You could use "to do as he said" but it would sound more formal than you probably want.

The first one would be asking someone else about their own dinner plans (not including you). The second is asking about dinner plans the speaker is included in. If it was already understood between the speakers that they're eating together, then these can be used interchangeably. Otherwise, they can be used to mean those two different things.

Not exactly. As a native speaker, referring to English as "textual" doesn't make a ton of sense. Some things you might be meaning there would be "text-based" or "grammatical" or "focused on grammar" or even "theoretical." Whereas the YouTube English you might be referring to might be more easily compared to those things by being called "functional" or "practical" or "focused on everyday usage" or "useful."

These terms come from specific American subcultures, so understanding them requires understanding the subcultures they come from. "Dragging" someone is publicly calling someone out (identifying their flaws, insulting them). It is often used in a playful or hyperbolic way among friends. If a friend lightly criticizes another, a third observing friend might say "OOH DRAG HIM." This is popular among black women, gay men and drag queens. Roasting someone is a bit more broadly used, but it is used to denote that someone is being playfully but harshly criticized. A "roast" might refer to a comedy segment where a public figure is honored by being publicly ridiculed by comedians. Everyday internet users might feel "roasted" if they're made fun of or criticized on the internet.

Alternative, he could be "giving you the cold ________" which body part?

The big question here is whether these words are describing "your points" - (ask "can points be clear points? maybe. can points be effective points? probably not.) or are these words describing how you "make" your points (can you make points clearly? yes. can you make points effectively? also yes.). As discussed below, that means that the words you're looking for are adverbs (modifying the verb make) and not adjectives (modifying the noun points).

A reader or a listener in English will probably understand what you mean, because English is full of idiosyncratic/metaphorical usages like this. These types of usages are very fashionable right now - turning nouns into verbs, using nouns more metaphorically/figuratively. However, I suspect the usage that is more common would be something along the lines of "find a PATH from Topic A to Topic B," which would be easily accepted as normal speech. A pathway refers to something like a corridor or trail, so if you were describing a sequence or a series of steps that needed to be taken to get from one point to another (figurative or literal), then pathway would work well to describe that linear movement (again, whether literal or figurative). In general, English is very forgiving of people using words in new/different figurative contexts, so when in doubt, I say go for it. It will likely only make you sound MORE fluent rather than LESS to use words in creative contexts for which they're not designed. (I know that sounds counter-intuitive, but it really is a very modern trend in English, especially among people in the business community, to make up new uses for words and then try to pass them off as totally normal.)