I look to Wortschatz A2 (Klett) and see this sentence how using "mitkommen".
Hallo da bist du ja, wie geht es dir? Gut. Und kommst du nun heute mit ins Kino oder nicht?
Why don't we have mit in the end and use it before ins Kino?
If you don't understand what's going on at the end of a sentence, use a predicate which has two parts. The second part goes into the verb-final position (rechte Klammer) and then you see where the other items really are. So the question is, which order will you get with a clause-final verb:
I'd say both are possible in principle, but the second version is a bit more difficult to get. "Ins Kino" sounds detached, maybe an afterthougt, and it cannot be stressed here, stress must fall on "mit", so "mit" is a regular verbal particle here (please don't call it "prefix"). The word order here is certainly more colloquial. German has a position after a clause-final verb (Nachfeld) but its use is somewhat restricted. Short phrases and core phrases often can't go there. But it is used somewhat more in the spoken language.
So the first version is easier to get. This has a different syntax, because "KINO" can get the stress in this case (but also MIT, I think). In this usage the syntax of "mit" is a bit special. Maybe it is a verbal particle, here too, or maybe it's an adverb, maybe both ... in any event it has a rather loose connection with the verb, and it can combine with other expressions. It's a very general pattern:
...plus the links that David Vogt has provided in his comment.
The word und at the beginning of a sentence is colloquial speech. Usually und connects two sentences, but in colloquial speech there are more reasons to use und, but this was not your question, so let's just analyze the sentence without it.
- Kommst du nun heute mit ins Kino oder nicht?
This would also be correct (and even preferred):
- Kommst du nun heute ins Kino mit oder nicht?
This would be wrong:
- Kommst du nun heute ins Kino oder nicht mit?
Let's start with #3:
The conjunction oder usually connects two equivalent parts of speech (two main clauses or elements of a list with the list's last element). But here the word nicht is an ellipsis that stands for a whole main clause:
Kommst du nun heute ins Kino mit oder kommst du nicht mit?
Subject (du) and verb (kommst ... mit) are equal, so they are not repeated in the second part, and so only the negation nicht remains. But still nicht stands for a whole main clause and the part before oder is another main clause, that ends before oder. But the former prefix mit of the separable verb mitkommen must stay in the same clause as the core of the verb (kommst), and therefore it can't stand somewhere after the conjunction oder.
So, let's omit that ellipsis, and let's talk about the actual main clause alone:
- Kommst du nun heute mit ins Kino?
- Kommst du nun heute ins Kino mit?
As said before, #2 is the preferred version, because the general rule is: The inflected past of the verb(s) must stand at position 2, all other verbs, including that particles, that are removed prefixes of separable verbs, must stand at the very end of the clause:
Ich gehe ins Kino.
Ich komme ins Kino mit.
Ich darf ins Kino gehen.
Ich darf ins Kino mitkommen.
Ich werde ins Kino gehen dürfen.
Ich werde ins Kino mitkommen dürfen.
So, but why is #1 still correct and often used (mainly in spoken German, less frequently in written German)?
There is a place in every clause, that usually is empty, so it's not occupied by any word. This place is called »Nachfeld« (literally: after-field). This is a place after the verb(s) that usually should stand at the very end of the sentence.
The verb at position 2 and the verb(s) at the last position can be very far away from each other in German sentences. There are authors from 19th century, who used to write sentences that cover are 2 or more pages in a book, so a whole short story can be told between the core part of a separable verb and the occurrence of its former prefix 2 pages later in the book. German native speakers are used to have lots of stuff between these two parts, that embrace the enclosed words like a bracket, so we use the term Verbklammer (literally: verbal bracket) to describe the situation that there is something between the different parts of the verb.
But sometimes it's also hard for native speakers to memorize the Verbklammern that can appear in longer sentences with enclosed clauses that have their own Verbklammern:
Ich kaufe gerne im Laden von Therese, die ich schon seit den 1980er-Jahren, in denen wir uns bei einem Fest, das damals die örtliche Feuerwehr, deren Kommandant ihr Vater war, veranstaltet hat, kennengelernt haben, kenne, ein.
Here a structured view of this sentence
Ich kaufe gerne im Laden von Therese,
die ich schon seit den 1980er-Jahren,
in denen wir uns bei einem Fest,
das damals die örtliche Feuerwehr,
deren Kommandant ihr Vater
Nobody (including 99% of all German native speakers) can remember correctly, which verb belongs to which clause. To make things simpler, we can move parts of speech, that usually should stand inside a Verbklammer, behind that bracket, into the Nachfeld:
Ich kaufe gerne im Laden von Therese ein, die ich schon seit den 1980er-Jahren kenne, in denen wir uns bei einem Fest kennengelernt haben, das damals die örtliche Feuerwehr veranstaltet hat, deren Kommandant ihr Vater war.
Putting parts of speech in the Nachfeld is unavoidable with sentences that are as complicated as the one in the last example. But it is also allowed with shorter sentences:
prepositional group ins Kino inside the Verbklammer:
Kommst du nun heute ins Kino mit?
prepositional group ins Kino in the Nachfeld:
Kommst du nun heute mit ins Kino?