W drodze do pracy kupuję kawę.

W drodze is a very common Polish expression meaning on the way or while traveling. In this sentence, W drodze do pracy means on the way to work.

It is not understood as inside a road. It is an idiomatic phrase about being in transit.

Because droga changes form after w in this expression.

• basic form: droga = road / way
• locative form: drodze

After w meaning in or during being in, Polish often uses the locative case. So:

• w drodze = on the way

This is also a fixed phrase, so learners should memorize w drodze as a chunk.

Because do means to / toward in the sense of movement toward a destination, and it requires the genitive case.

• basic form: praca = work
• genitive form: pracy

So:

• do pracy = to work

In natural English, this often means to my workplace or simply to work, not necessarily to the abstract concept of work.

Because do always takes the genitive, not the accusative.

Compare:

• do pracy = to work → genitive
• widzę pracę = I see the work/job → accusative

So in your sentence, pracy is there because of the preposition do, not because it is the object of the verb.

Kupuję is the imperfective verb form. It is used for actions that are:

• habitual
• repeated
• ongoing, depending on context

So kupuję kawę often means I buy coffee or I am buying coffee.

By contrast, kupię is perfective and usually refers to a completed future action:

• kupię kawę = I will buy coffee

In this sentence, kupuję is the natural choice because it suggests a routine: On the way to work, I buy coffee.

It can mean either, depending on context.

The Polish present tense of an imperfective verb often covers both:

• I buy
• I am buying

In this sentence, the most likely meaning is habitual:

• On the way to work, I buy coffee

That is because w drodze do pracy often sounds like part of a routine.

Because kawa is the direct object of kupuję, and feminine nouns usually take the accusative in that role.

• nominative: kawa = coffee
• accusative: kawę

So:

• Kupuję kawę = I buy coffee

This is one of the most important patterns in Polish: the object often changes form.

Because Polish often drops subject pronouns when they are already clear from the verb ending.

• kupuję already means I buy
• the ending -ę tells you the subject is I

So Ja kupuję kawę is possible, but ja is usually added only for emphasis, contrast, or clarity.

For example:

• Ja kupuję kawę, a on herbatę. = I’m buying coffee, and he’s buying tea.

Yes. Polish word order is fairly flexible, although the different versions can sound slightly different in emphasis.

Your sentence:

• W drodze do pracy kupuję kawę.

This puts the setting first: On the way to work...

Other possible orders:

• Kupuję kawę w drodze do pracy.
• Kawę kupuję w drodze do pracy.

These all mean roughly the same thing, but the focus changes:

• sentence-initial W drodze do pracy emphasizes when / under what circumstances
• sentence-initial Kawę emphasizes coffee

The version you gave is very natural.

Yes, but the nuance is a little different.

• w drodze do pracy = on the way to work, while going to work
• po drodze do pracy = along the way to work / on the way to work, often with the sense of stopping somewhere en route

So:

• W drodze do pracy kupuję kawę sounds like a general statement about what I do while going to work.
• Po drodze do pracy kupuję kawę can sound a bit more like I pick up coffee on the way.

Both are possible, but w drodze do pracy is a very standard, neutral phrasing.

Because na drodze usually means on the road or on the path in a more literal sense, or sometimes in the course of in a formal style.

For everyday on the way to work, Polish normally says:

• w drodze do pracy

So:

• na drodze do pracy would not be the normal choice here
• w drodze do pracy is the idiomatic expression you want

Yes, very often it does.

Because of kupuję in the imperfective present, many listeners will understand this as a habitual action:

• On my way to work, I buy coffee.

If you wanted to stress a one-time future action, you would use something like:

• W drodze do pracy kupię kawę. = I’ll buy coffee on the way to work.

So the original sentence most naturally sounds like part of a routine.