Learn Hardcore Chinese: wǒ xiàbān yǐhòu bù xiǎng chūmén.

So 我下班以后不想出门 is better understood as:
“After I get off work, I don’t want to go out.”
not just “After work (in general) I don’t want to go out.”

Why is 以后 (yǐhòu) used here? Could I leave it out?

以后 means “after / later” and marks a time after something.

我下班以后不想出门。
“I don’t want to go out after I get off work.”

If you say 我下班不想出门, it sounds incomplete or odd, because 下班 usually needs something like 以后 or 了 to make the “after finishing work” time clearer.

You can say:

下了班以后，我不想出门。 (very natural)
下班以后，我不想出门。 (also natural)

Leaving 以后 out usually requires 了:

下了班，我就不想出门。
“Once I’m off work, I don’t want to go out.”

Can I move 下班以后 to the beginning of the sentence?

Yes. Time expressions are very flexible in Chinese. Both are natural:

我下班以后不想出门。
下班以后，我不想出门。

Putting 下班以后 at the beginning is slightly more “topic-comment” and sounds very natural in spoken Chinese:
“As for after work, I don’t want to go out.”

Why is it 不想 (bù xiǎng) and not 不要 (bú yào)? What’s the difference?

Both can relate to “not wanting”, but the nuance is different:

不想出门 = “don’t feel like going out / don’t want to go out (inwardly, by preference)”
- softer, about inner desire / inclination
不要出门 = “don’t go out / don’t you go out”
- often sounds like a command / instruction / warning

In your sentence, we’re talking about how I feel, so 不想出门 is the natural choice.
不要出门 would sound like telling someone else “Don’t go out.”

Does 想 (xiǎng) here mean “think” or “want”?

In this sentence, 想 means “to want / to feel like (doing something)”.

Common meanings of 想:

want to / feel like
- 我想吃饭。 = I want to eat.
think / consider
- 我想，这样不太好。 = I think this isn’t very good.
miss (someone)
- 我很想你。 = I miss you a lot.

Context tells you the meaning. With a verb right after (想出门), it usually means “want to / feel like (doing X)”.

What exactly does 出门 (chūmén) mean? Is it the same as 出去 (chūqù)?

They’re related but not exactly the same:

出门 = to go out (of the house / door / indoors), often implying “go out in general”
- 我不想出门。 = I don’t want to go out (leave home / go outside).
出去 = “go out” in a more directional sense (outwards from here).
- 我要出去一下。 = I’m going out for a bit.

In your sentence, 出门 is perfect: it expresses the general idea of leaving home / going out without specifying the direction too precisely.

Could I say 我下班以后不想出去 instead of 出门?

Yes, you can say 不想出去, and it’s also natural. Nuance:

不想出门 – emphasizes leaving the door/home/indoors; very common in everyday speech.
不想出去 – emphasizes the direction “out(wards)” from where you are.

In practice, in this context, both usually mean basically the same:
“I don’t feel like going out after work.”

Can I drop the 我 (wǒ) and just say 下班以后不想出门?

Yes, in a suitable context you can omit 我, and people will understand it refers to you:

(我) 下班以后不想出门。

Chinese often drops the subject when it’s obvious from context.
But in isolation (like in a textbook example), including 我 is clearer.

Why isn’t there a past tense marker like “-ed”? How do we know if this is about past, present, or future?

Chinese doesn’t use verb changes (like work / worked) for tense.
Time is usually expressed with time words and context, here:

下班以后 = after (I) get off work

Depending on context, the sentence could mean:

general habit:
- “After work, I (generally) don’t want to go out.”
about today / future:
- “After I get off work (today), I don’t want to go out.”

If you need to be specific, you add time words:

今天下班以后，我不想出门。
After work today, I don’t want to go out.
以后下班以后，我都不想出门。
In the future, after work I never feel like going out.

Can I say 我下了班以后不想出门? What’s the difference between 下班以后 and 下了班以后?

Both are grammatical and common:

我下班以后不想出门。
我下了班以后不想出门。

Nuance:

下班以后 – a bit more neutral and slightly more “timeless” / general.
下了班以后 – 了 can make the action feel more clearly completed, often fitting concrete situations (today, a specific time), e.g.:
- “After I’ve finished work, I don’t want to go out.”

In everyday speech, people use both; the difference is subtle.

Could I say 我以后下班不想出门 instead? Where should 以后 go?

Putting 以后 right after 我 changes the meaning:

我下班以后不想出门。
= After I get off work, I don’t want to go out.
我以后下班不想出门。
Literally: “I in the future, when I get off work, don’t want to go out.”
This sounds awkward and unclear; it seems to say “from now on, whenever I get off work, I don’t want to go out”, but native speakers would phrase that differently:
- 以后我下班就不想出门了。
- 以后下班我都不想出门。

So for the simple “after work, I don’t want to go out,” keep 以后 after 下班:
下班以后.

Is 不 in 不想 pronounced bù or bú here?

In isolation, 不 is bù (4th tone), but there is a tone sandhi rule:

不 changes to bú (2nd tone) when followed by a 4th-tone syllable.

想 (xiǎng) is 3rd tone, so 不 stays bù:

不想 (bù xiǎng)

Examples of the change:

不对 → bú duì
不是 → bú shì

So in your sentence it’s: wǒ xiàbān yǐhòu bù xiǎng chūmén.