Перед выходом я быстро надел кеды и пошёл в парк.

Because перед normally takes the instrumental case when it means before or in front of.

So:

• выход = exit / going out / departure
• перед выходом = before going out / before leaving

This is a very common pattern:

• перед уроком = before class
• перед сном = before sleep / before going to bed
• перед отъездом = before departure

In this sentence, перед выходом is an adverbial phrase meaning before leaving.

Because перед выходом is just a short prepositional phrase, not a full clause.

Russian usually does not put a comma after a simple introductory time phrase like this:

• Перед выходом я быстро надел кеды...

But if you used a full clause, then a comma would appear:

• Перед тем, как выйти, я быстро надел кеды...

So the difference is:

• перед выходом = noun phrase, no comma
• перед тем, как выйти = clause structure, comma needed

This is a very common learner question. Russian distinguishes:

• надеть = to put on something
• одеть = to dress someone

So:

• надеть кеды = to put on sneakers
• одеть ребёнка = to dress a child

Here the speaker is putting footwear on himself, so надел кеды is correct.

A helpful memory trick is:

• надеть что? = put on what?
• одеть кого? = dress whom?

Кеды is the object of надел, so it is in the accusative case.

However, because кеды is an inanimate plural noun, its accusative plural looks the same as the nominative plural:

• nominative: кеды
• accusative: кеды

So even though the case is accusative, the form does not change.

Also, footwear words like this are very often used in the plural in Russian, since they naturally refer to a pair.

Not exactly. Кеды refers specifically to casual rubber-soled sneakers or canvas shoes, something like sneakers, trainers, or plimsolls depending on context.

It is more specific than:

• обувь = footwear
• туфли = dress shoes / low shoes
• ботинки = boots / ankle boots / sturdy shoes

So кеды gives a more concrete picture of what the speaker put on.

Because that is a natural place for an adverb in Russian.

Быстро modifies the action надел, so putting it before the verb sounds neutral and natural:

• я быстро надел кеды

Russian word order is flexible, so other positions are possible, but they can change emphasis:

• Я быстро надел кеды = neutral, natural
• Я надел кеды быстро = stronger focus on quickly, often more contrastive
• Быстро я надел кеды... = marked or stylistic

So the sentence uses the most ordinary word order.

Because пошёл focuses on the action as a single completed step: set off / went.

Compare:

• пошёл в парк = went off to the park, started going and did it as the next event
• шёл в парк = was walking to the park / was on the way to the park

In this sentence, the speaker lists actions in sequence:

1. put on sneakers
2. went to the park

That makes пошёл a very good choice.

Because Russian uses different cases depending on whether you mean movement toward a place or location in a place.

• в парк = into / to the park → accusative
• в парке = in the park → prepositional

So:

• пошёл в парк = went to the park
• был в парке = was in the park

This is a basic and very important Russian pattern.

In the past tense, Russian verbs agree with the subject in gender and number.

So with я:

• a male speaker says надел, пошёл
• a female speaker says надела, пошла

This sentence therefore suggests that the speaker is male.

The full female version would be:

• Перед выходом я быстро надела кеды и пошла в парк.

Because the sentence presents two complete, one-time actions in sequence.

• надел from надеть = put on
• пошёл from пойти = went / set off

Perfective aspect is very common when telling a story as a chain of completed events:

• did X
• then did Y

If you used imperfective verbs instead, the meaning would become more process-based, descriptive, habitual, or context-dependent.

So the perfective aspect here helps the sentence sound like a clear, finished event.

Yes, it can be omitted if the subject is already clear from context.

For example:

• Перед выходом быстро надел кеды и пошёл в парк.

This can work in narration, especially if everyone already knows who is being talked about.

However, keeping я is often clearer, because past tense verb forms in Russian show gender and number, but not person. Without я, the sentence may rely more on context to identify the subject.

So in isolation, я is helpful and natural.

Yes. Russian word order is flexible, but changing it changes emphasis.

The original:

• Перед выходом я быстро надел кеды и пошёл в парк.

is a neutral, natural way to say it.

Possible variations:

• Я перед выходом быстро надел кеды и пошёл в парк.
  Slightly more focus on I.

• Кеды я быстро надел перед выходом и пошёл в парк.
  More emphasis on кеды.

• В парк я пошёл, быстро надев кеды перед выходом.
  Much more literary or stylistically marked.

So yes, the order can change, but the original is the most straightforward for everyday speech.