Learn Hardcore Swedish: Jag vill inte vänta länge.

You usually do not say: Jag inte vill vänta länge in neutral, everyday speech. That word order is wrong in a normal statement (though you can front inte for special emphasis, see another answer below).

Why is it länge and not lång?

Lång is an adjective meaning “long” (describing a noun):

en lång dag – a long day
en lång film – a long film

Länge is the adverb meaning “for a long time / long” (describing how long an action lasts):

vänta länge – wait long / wait for a long time
bo länge i Sverige – live in Sweden for a long time

In Jag vill inte vänta länge, you are describing the duration of the action vänta, so you must use the adverb länge, not the adjective lång.

Why isn’t there an att before vänta? Shouldn’t it be vill att vänta?

Some Swedish verbs take the infinitive without att, and vilja (vill) is one of them.

Jag vill vänta. – I want to wait.
Jag vill inte vänta.

You do not say: Jag vill att vänta.

Typical verbs that usually take a bare infinitive (without att) include:

vill (want to)
kan (can)
ska (shall / will)
måste (must)
brukar (usually)

Compare with verbs that do need att:

Jag försöker att vänta. – I try to wait.
Jag gillar att vänta. – I like to wait.

Could you say Jag vill inte länge vänta or Jag vill länge inte vänta?

Those versions sound wrong or at best very unnatural in modern Swedish.

The natural word order is:

Jag vill inte vänta länge.

General pattern with these elements:

Subject: Jag
Finite verb: vill
Negation: inte
Infinitive phrase: vänta länge (verb + time adverb)

Moving länge in between the verbs or in front of inte breaks normal word order and rhythm. Native speakers would not say this unless they were doing something very marked or poetic, and even then it would be odd.

What is the difference between länge and för länge?

länge = long, for a long time (neutral duration)
för länge = too long, for too long (excessive duration)

Compare:

Jag vill inte vänta länge.
I don’t want to wait long / for a long time.
Jag vill inte vänta för länge.
I don’t want to wait too long.

So för länge adds the idea of “more than is acceptable/desired.”

What’s the difference between länge and längre in this kind of sentence?

länge = (for) a long time (in general)
längre = longer / any longer (comparative of lång/länge)

So:

Jag vill inte vänta länge.
I don’t want to wait (for) a long time.
Jag vill inte vänta längre.
I don’t want to wait any longer / I don’t want to keep waiting.

Längre usually implies continuing something beyond the current point, while länge is more about the general length of time.

Is there a difference between Jag vill inte vänta länge and Jag vill inte vänta så länge?

Yes, but it’s subtle:

Jag vill inte vänta länge.
Neutral: I don’t want to wait long.
Jag vill inte vänta så länge.
More specific/relative: I don’t want to wait that long / that much.

Så länge often implies some kind of reference point: you’ve been told a certain time, or you’re imagining a specific duration, and you’re saying it’s too much.

How do I turn this into a yes–no question: “Don’t you want to wait long?” in Swedish?

In Swedish, you normally keep the same basic order (finite verb before inte), but move the verb to first position and add the subject after it.

Statement:

Du vill inte vänta länge. – You don’t want to wait long.

Yes–no question:

Vill du inte vänta länge? – Don’t you want to wait long?

Pattern:

Verb: Vill
Subject: du
Negation: inte
Rest: vänta länge

Can inte be put at the beginning, like Inte vill jag vänta länge?

Yes, that is possible, but it’s used for emphasis and is more stylistic/literary.

Inte vill jag vänta länge.
Roughly: “I certainly don’t want to wait long,” or “No, I don’t want to wait long.”

When you move inte (or any adverbial) to the front, the verb must come second (V2 rule), so vill comes second and jag moves after the verb.

This is not the neutral word order you’d use in everyday speech; it adds an emotional or contrastive nuance.

How would I say “I won’t wait long” rather than “I don’t want to wait long”?

Your original sentence expresses desire/willingness:

Jag vill inte vänta länge. – I don’t want to wait long.

If you want to express a more factual future decision (“I’m not going to wait long”), you can say:

Jag kommer inte att vänta länge. – I will not wait long / I’m not going to wait long.
Jag tänker inte vänta länge. – I’m not intending to wait long / I’m not going to wait long.

All of these are possible; the choice depends on whether you’re talking about your wish (vill) or your planned/future action (kommer att, tänker).

Can I drop Jag and just say Vill inte vänta länge?

You can omit Jag in very informal contexts where it’s clear who is speaking, especially in writing (texts, chats) or casual speech:

Vill inte vänta länge. – (I) don’t want to wait long.

Grammatically, the full form Jag vill inte vänta länge is standard and always correct. Dropping the subject is more of a colloquial shortcut, not suitable for formal writing or careful spoken Swedish.

How would I say this as a command: “Don’t wait long”?

As an imperative (a direct instruction), you use the verb in its imperative form and drop vill:

Vänta inte länge. – Don’t wait long.

Structure:

Vänta – imperative
inte – negation
länge – time adverb

So:

Statement about desire: Jag vill inte vänta länge.
Command: Vänta inte länge.