Learn Hardcore Russian: Сейчас я иду в парк, а обычно я хожу туда пешком. - Right now I am going to the park, and usually I walk there on foot.

идти – movement right now / in one specific direction / one trip
ходить – movement in general / habitually / back-and-forth or multiple times

So:

Сейчас я иду в парк – иду: I’m (in the process of) going to the park now, one specific trip.
Обычно я хожу туда пешком – хожу: I usually go there on foot, as a regular habit, many times.

English uses one verb (go) and expresses the difference with adverbs (now vs usually). Russian encodes part of that difference in the verb itself.

Could I say Сейчас я хожу в парк instead of Сейчас я иду в парк? What would it mean?

You can say Сейчас я хожу в парк, but it means something different:

Сейчас я иду в парк – I’m on my way to the park right now / I’m just going there now.
Сейчас я хожу в парк – Nowadays / at this period of my life, I go to the park regularly.

So сейчас can mean:

“right now, at this moment” → then use иду
“these days / at present (in my life)” → then use хожу to talk about a current habit

In your sentence, we clearly talk about the current trip, so иду is correct.

Is иду present tense or future? Could it mean “I am going to go to the park (soon)”?

Formally, иду is present tense.

But Russian motion verbs like идти can express:

present in progress:
Я иду в парк. – I am (already) walking to the park.
immediate, planned future (especially with сейчас, завтра утром etc.):
Сейчас я иду в парк. – I’m going to the park now / I’m about to go to the park.

Context decides whether you’re already physically walking or just about to leave. English would normally use a continuous form for both: I’m going to the park (now / in a minute).

Why is it иду, not еду? What’s the difference?

Russian distinguishes going on foot vs going by transport:

идти / ходить – to go on foot
ехать / ездить – to go by transport (car, bus, train, bike, etc.)

In your sentence, the second clause says я хожу туда пешком (I go there on foot), so it’s clear that the mode is walking. That’s why the first verb is иду, not еду.

If you usually went by bus, you would say something like:

Сейчас я еду в парк, а обычно я езжу туда на автобусе.
(Now I’m going to the park, and usually I go there by bus.)

Why is it в парк and not в парке?

The preposition в can take different cases:

Accusative (куда? – to where?) → в парк = “to the park”
Prepositional (где? – where?) → в парке = “in the park”

Here the meaning is going to the park (direction), so we use в парк (accusative).
If you wanted to say “I am in the park”, you’d say:

Я в парке. – I am in the park.

Why do we say туда and not там?

The pair is:

там – there (location, “in that place”)
туда – there (direction, “to that place”)

In your sentence, туда refers back to в парк and keeps the idea of movement to that place:

я хожу туда – I go there (to that place)

If you said я хожу там, it would mean “I walk there (in that place)”, focusing on being/walking inside that place, not on going to it.

Is it redundant to say both в парк and туда? Could I leave one out?

It’s not redundant; it’s very natural.

First clause: иду в парк – introduces the place.
Second clause: хожу туда – uses туда = “to there”, referring back to в парк.

You could say:

Сейчас я иду в парк, а обычно я хожу пешком. – OK, but less explicit; we infer “there”.
Сейчас я иду туда, а обычно я хожу туда пешком. – also OK, if the place was mentioned earlier.

Using в парк first and then туда later is a common, coherent way to connect the two clauses.

What exactly does пешком mean, and where can it go in the sentence?

Пешком means “on foot, by walking”. Literally it comes from пеший (“on foot”).

Typical patterns:

идти пешком – to go on foot (this time)
ходить пешком – to go on foot (habitually)
Я хожу туда пешком. – I go there on foot.

Word order is flexible. You might see:

Я хожу туда пешком.
Я пешком хожу туда.

The most neutral here is exactly what you have: я хожу туда пешком (adverbial phrase at the end).

Why is the conjunction а used here, and not и or но?

Russian has several coordinating conjunctions:

и – “and”, simply adding information.
но – “but”, a strong contrast / opposition.
а – a weaker, often contrastive “and”, like “and (whereas)” / “but on the other hand”.

In your sentence:

Сейчас я иду в парк, а обычно я хожу туда пешком.

We contrast the current situation (now I’m going) with the usual pattern (normally I walk). It’s not a strong opposition, just a difference, so а fits best.

И would feel too “flat”, without contrast.
Но would sound too strong, like the usual way is in conflict with what is happening now.

Why is there a comma before а?

The sentence has two independent clauses:

Сейчас я иду в парк
обычно я хожу туда пешком

They are joined by the coordinating conjunction а. In Russian, when two full clauses (each with its own subject and verb) are joined with а, we normally put a comma before а:

…, а …

So the comma simply separates the two clauses:

Сейчас я иду в парк, а обычно я хожу туда пешком.

Could we change the word order, like Я сейчас иду в парк or Обычно я хожу туда пешком? Any difference?

Yes, Russian word order is quite flexible. Common variants:

Сейчас я иду в парк.
Я сейчас иду в парк.

Both are natural. Сейчас at the beginning slightly emphasizes the time (“Now, I’m going to the park”). In everyday speech, Я сейчас иду в парк is probably even more common.

With обычно:

Обычно я хожу туда пешком. – neutral, slight emphasis on “usually”.
Я обычно хожу туда пешком. – also neutral; the focus is very similar.

All of these are correct; differences are subtle and mostly about which part you highlight.

Russian has no articles. How do we know if в парк means “to a park” or “to the park”?

Russian в парк doesn’t specify “a” vs “the” by itself. Context does the job.

If it’s a known, specific park (for both speakers), English will usually translate в парк as to the park.
If it’s just any park, English might use to a park.

In everyday contexts, people often have a “default” local park in mind, so иду в парк is usually understood as “I’m going to the park (that we both know about).”

Could we use пойду instead of иду here? What’s the difference between я иду and я пойду?

Both come from идти, but:

иду – imperfective present; stresses process / ongoing action.
пойду – perfective future; stresses the start or single occurrence of the action.

Compare:

Сейчас я иду в парк. – I’m (on my way) to the park now / I’m going now.
Сейчас я пойду в парк. – I’ll go to the park now / I’m about to set off to the park.

In your sentence, иду is better because we describe the actual current trip, not just the decision or the moment of starting.