Question tags usually have two purposes: to indicate a lack of certainty ("You're Indian, aren't you?" "No, I'm from Pakistan"), or to confront ("You won't be late next time, will you?" "No, sir. I'm sorry").

Both of these functions are very common in spoken language, less in written language, because normally readers don't respond to texts. They just read and think.

Of course, if you expect a personal response from one person (eg. online chatting), then it's fine.

Here I am writing for the italki community, so I won't use a question tag. But if I were writing to you personally I might write "You understand question tags now, don't you?" ;-)

"extraordinary" is very rarely pronounced "extra ordinary". When done so, it's often used for humorous, emphatic effect.

"Extrordinary" or "extrordnry" are better pronunciations. If you check the word on Forvo.com, the first two pronunciations (by the users anakat and Picadilly) are the best. The third (by the user TopQuark), while not incorrect, is very formal.

When I first heard that Persian verb stems all have two stems (or even more counting the spoken forms of some verbs like گفتن) I was terrified. Luckily, I quickly discovered that most Persian verbs are noun-verb compounds, using a handful of delexicalised verbs like کردن، گرفتن، دادن, etc. and that memorising a small handful of stems can get you a long way.

In case the term "delexicalised verb" is unfamiliar, it's basically a meaningless verb that does nothing except act a noun. For example, گرفتن can have the meaningful, lexical meaning of "get", eg. او کتاب را از دستم گرفت (he got/grabbed the book from my hand), but it's very often delexicalised, for example تصمیم گفتن (to decide, lit. "get a decision"): چرا تصميم گرفتی يه معلم بشی؟ (Why did you decide to become a teacher?), translated word-for-word means *"Why did you get the decision to become a teacher?").

Obviously, here گرفتن (get) is totally meaningless, it has no real use except to complement تصمیم (decision)

English has delexicalised verbs too, used especially in speaking. For example, we can "try" or "have a try", we can "advise" or "give advice", we can "shower" or "take a shower". However it's astonishing just how many Persian verbs are delexicalised.

(Note: this is just my humble opinion as a learner of Persian, if any native Persian-speakers disagree I'm happy to learn from your comments!)

Yes. Incorrect adjective order will make any native speaker's ears prickle.

There are many rules around adjective order, but here's a basic one to get you started:

Gradable adjectives before ungradable adjectives.

For example, "the big brown dog played with the bouncy rubber ball" (not: "the brown big dog played with the rubber bouncy ball")

"Big" and "bouncy" are gradable, because we can say "X is bigger/bouncier than Y". "Brown" and "rubber" are ungradable because we don't usually say "X is browner/more rubber than Y".

This is why "big brown" and "bouncy rubber" sound much more natural than the reverse.