Learn Hardcore Chinese: Wǒ mǎshàng qù gōngsī, nǐ zài jiā děng wǒ ba. - I’m going to the company right away; wait for me at home.

It softens the command into a friendly suggestion. With 吧 (ba), 你在家等我吧 is like “Why don’t you wait for me at home,” or “Wait for me at home, okay?” Without 吧, it sounds more like a firm instruction.

Can I drop 吧? How does it change the tone?

Yes. 你在家等我。 is grammatically fine but more direct and potentially a bit curt. To be even softer or explicitly ask for agreement, you can say:

你在家等我，好吗/可以吗/行吗？

Is 在 here the “progressive” marker (like “be doing”), or just a location?

Here it’s a location phrase: 在家 = “at home.” The structure is Subject + Place + Verb + Object: 你在家等我.
The progressive marker use would be 你在等我吗？ or 你正在等我吗？ (“Are you waiting for me?”).

Where does 马上 go? Could I say 我去公司马上?

Place 马上 (right away) before the verb phrase: 我马上去公司. Common variants:

我马上就去公司。 (adds emphasis with 就)
马上就去公司。 (subject omitted in context) Avoid 我去公司马上; that word order is unnatural.

Why is there no “to” word like 到 before 公司? Is 去到公司 okay?

In Mandarin, motion verbs can take a place directly: 去公司、回家、进学校.
Use 到 when emphasizing arrival: 到公司了 (“arrived at the company”).
去到公司 is regionally common (e.g., in Southern varieties) but in standard Putonghua you usually just say 去公司.

What’s the difference between 公司, 办公室, 单位, and 公司里?

公司: “company/office (as workplace).” Everyday way to say “the office.”
办公室: “office room.” A specific office (the room/department).
单位: “work unit/organization,” often formal or public-sector.
公司里(面)/公司内: “inside the company/office,” adds the idea of being inside.

Should it be 去 or 来? When would 我马上来公司 be correct?

Use 去 when moving away from your current location: 我马上去公司.
Use 来 when moving toward the listener’s or speaker’s location. For example, if you’re on the phone with a colleague who is at the company, you can say 我马上来公司 (“I’m coming to the office [where you are] right away”).

Do I need 了 to show “about to” in 我马上去公司?

Not required. 我马上去公司 already means “I’m going right away.”
Adding 了 gives a stronger “it’s happening now/about to happen” feeling:

我马上去公司了。 (“I’m heading to the office now / about to go.”)

What’s the nuance of adding 着 after 等, like 你在家等着我吧?

等 = wait; 等着 often highlights the ongoing, continuous state of waiting.

你在家等我吧。 neutral request.
你在家等着我吧。 “keep waiting for me at home.”
Note: 等着我！ alone can sound like “Just you wait!” (a challenge) depending on tone/context.

Does 等 need a “for,” like “wait for me”? How do I make it more polite?

Chinese 等 can be transitive: 等我、等车、等雨停. No extra preposition is needed.
To soften: 等我一下/等我一会儿 (“wait for me a moment / a while”).

Any pronunciation tips? What about tone sandhi?

我 wǒ
- 马 mǎ (two 3rd tones): the first becomes 2nd tone → say wó mǎshàng.
等 děng
- 我 wǒ (two 3rd tones): the first becomes 2nd tone → déng wǒ.
吧 is neutral tone (ba).
Natural reading: wó mǎshàng qù gōngsī, nǐ zài jiā déng wǒ ba.

Does 在家 mean “at my home,” “at your home,” or just “at home”? Should I say 在我的家?

在家 means “at (one’s) home,” defaulting to the subject’s home. In 你在家, it’s “at your home.”
To specify, use 在我家/在你家/在他家. 在我的家 is grammatically okay but less natural than 在我家.

Is this a question because of 吧? Should I use a question mark?

With 吧 and a period, it’s a suggestion/request, not a question.
To make it a confirmation question, write 你在家等我吧？ with rising intonation (“You’ll wait at home, right?”) or use 好吗/可以吗 at the end.

How else can I soften or strengthen the request?

Softer: 你在家等我一下，好吗？ / 麻烦你在家等我一下。
Neutral: 你在家等我吧。
Stronger/direct: 你在家等我。

Are there other ways to say “right away/soon,” and do they differ from 马上?

马上、立刻、立即: “immediately.” 立即 is more formal; 马上 is neutral colloquial.
很快就…: “very soon …” (less instantaneous).
快要…了/就要…了: “about to …”
Examples: 我很快就去公司。/ 我快要去公司了。/ 我立即去公司。

Could I say “I’m going to work” instead of “I’m going to the company”?

Yes:

我马上去上班。 (“I’m going to work right away.”)
我马上要上班了。 (“I’m about to start work.”)
Use 去公司 when you mean the place; 上班 when you mean the activity of working.