tā guān dēng le, tā guān mén le.

Both are correct, but the nuance differs:

• 她关灯了: sentence-final 了 highlights the new situation now.
• 她关了灯: verb-了 highlights completion of the action. In many contexts they’re interchangeable. You’ll also hear both combined in casual speech: 她关了灯了, though one 了 is usually enough in careful writing.

Very common and natural. Use 把 to foreground the affected object:

• 她把灯关了。
• 他把门关了。 把 is preferred when the object is specific/known and you want to stress the result on that object.

Yes. 关门 also means “close for business.” Disambiguate with context:

• He closed the door: 他把门关了。/ 他关上门了。
• The shop is closed: 商店关门了。
• He closed his shop: 他的店关门了。

Use 没(有) for past/completed events and drop 了:

• 她没关灯。
• 他没关门。 To say “not yet,” use 还没(有):
• 她还没关灯。
• 他还没关门。 Don’t use 不 to negate completed past actions; 不关门了 means “(he) won’t close the door anymore,” a different meaning.

Place them before the verb phrase; 了 often still appears:

• 她已经关灯了。
• 他刚关门。/ 他刚关门了。 (both heard; 了 adds the “now it’s done” feel) Typical order: Time > manner/adverbs > place > subject’s verb phrase is also common in spoken Chinese flexibility.

The comma simply coordinates two clauses, much like “and.” You normally don’t use 和 to join whole clauses. If you want to make the link explicit:

• Addition: 她关灯了，他也关门了。
• Sequence: 她关灯了，然后他关门了。

Use a single subject and link the verbs:

• 她关了灯又关了门。
• 她把灯和门都关了。
• 她先关灯，然后关门。

Better to be consistent if both actions are similarly completed. 她关灯，他关门了 sounds lopsided. Prefer:

• 她关灯了，他关门了。
• 她关了灯，他关了门。 Or add a time word that clearly sets the actions in the past.

Only when specifying number or using a demonstrative:

• 一盏灯 (one lamp/light), 那盏灯
• 一扇门 (one door), 这扇门 Examples: 她关了那盏灯，他关了这扇门。

Yes, if context is clear:

• 关灯了，关门了。 Chinese often drops known subjects to sound natural and concise.