پول ندارم، پس امروز در خانه هستم.

Yes. It’s the negative of دارم (I have).

• دارم = I have (present)
• ندارم = I don’t have

In everyday Persian, possession is usually expressed with داشتن (to have) in this simple present form, so پول ندارم is the normal way to say I don’t have money.

Because نمی‌دارم usually means I don’t hold / I’m not holding (from داشتن in the sense of holding/keeping), and it can sound unnatural for possession.
For possession, Persian strongly prefers:

• پول ندارم = I don’t have money

So نـ + دارم → ندارم is the idiomatic possession pattern.

By default, پول ندارم means I don’t have money / I’m broke in a general sense.
If you specifically mean I don’t have money on me, Persian often adds clarification, for example:

• پول همراهَم نیست = I don’t have money with me.
• پول توی جیبم نیست = I don’t have money in my pocket.

پس means so / therefore / then and links the first clause (cause) to the second clause (result). It commonly comes at the start of the result clause:

• پول ندارم، پس امروز در خانه هستم. = I don’t have money, so today I’m at home.

You can also use close alternatives depending on style:

• برای همین (more colloquial: that’s why)
• بنابراین (more formal: therefore)
• پس is neutral and very common.

Yes, but the structure flips emphasis:

• With پس: cause → so → result
  پول ندارم، پس امروز در خانه هستم.
• With چون: because → cause → result
  چون پول ندارم، امروز در خانه هستم. = Because I don’t have money, I’m at home today.

Both are correct; چون frontloads the reason.

Yes, time words like امروز are flexible. These all work, with slightly different emphasis:

• پس امروز در خانه هستم (today is highlighted early)
• پس در خانه هستم امروز (more marked / less common in careful speech)
• امروز در خانه هستم (simple, very natural)

The most natural placements are early in the clause.

Literally it’s I am in the house, but in Persian this is a standard way to mean I’m at home.
Common alternatives:

• خونه‌ام (colloquial) = I’m home.
• توی خونه‌ام (colloquial) = I’m at home / in the house.
• در خانه هستم is more neutral/formal.

In the present tense, Persian often omits هستم (especially in speech), but it depends on the structure.

• In conversation, you might hear: پس امروز خونه‌ام.
• With در خانه, many speakers still keep the verb: امروز در خانه هستم.

Keeping هستم is always safe and clear.

A very natural colloquial version would be:

• پول ندارم، پس امروز خونه‌ام.
  Or even:
• پول ندارم، برای همین امروز خونه‌ام.

Spoken Persian typically uses خونه instead of خانه, and often drops هستم.

Yes. Adding -ی can make it feel more like any/some in negative contexts:

• پولی ندارم = I don’t have any money.

Both پول ندارم and پولی ندارم are common; پولی ندارم can sound a bit more emphatic or explicit about any amount.

A common conversational pronunciation (Tehrani-style) would be close to:

• pul nadâram, pas emruz dar xune hastam
  And an even more colloquial version:
• pul nadâram, pas emruz xune-am

Notes:

• خ is a throaty sound like German Bach.
• â is a long a (as in father).