Если я встаю рано, я успеваю позавтракать дома.

Because Russian puts a comma between the if-clause and the main clause.

• Если я встаю рано, я успеваю позавтракать дома.

This is the same basic idea as English If I get up early, I manage to have breakfast at home.

Russian normally uses a comma with clauses introduced by если.

Если normally means if. In sentences like this, though, it often expresses a general condition, so in natural English it can feel close to when:

• Если я встаю рано... = If/When I get up early...

The meaning is not about one specific future event only. It describes a repeated pattern: whenever that condition is true, the result happens.

Because the sentence describes a habitual/repeated situation, not one single completed future action.

• встаю = I get up / I am in the habit of getting up
• встану = I will get up once, in the future

So:

• Если я встаю рано... = If I get up early / When I get up early
• Если я встану рано... would mean If I get up early (on a particular future occasion)

In general statements, Russian usually prefers the imperfective.

For the same reason: this sentence describes something that generally happens.

• успеваю = I manage / I have enough time
• успею = I will manage / I will have enough time on one future occasion

So this sentence means something like: When I get up early, I manage to have breakfast at home. It is about a regular result, not a single future event.

The verb успевать / успеть often means to manage to do something or to have time to do something, and it is commonly followed by an infinitive.

Pattern:

• успевать + infinitive
• успеть + infinitive

Examples:

• Я успеваю прочитать письмо. = I manage to read the letter.
• Ты успеешь прийти? = Will you have time to come?

So успеваю позавтракать means I manage to have breakfast / I have time to eat breakfast.

Because after успеваю, Russian often uses a verb that refers to the action as a completed whole.

• завтракать = to be having breakfast / to have breakfast in general
• позавтракать = to have breakfast, viewed as a completed event

Here the idea is: I have enough time to finish having breakfast before I leave. That is why позавтракать sounds natural.

Compare:

• Я люблю завтракать дома. = I like having breakfast at home.
  
  • general activity, so imperfective
• Я успеваю позавтракать дома. = I manage to have breakfast at home.
  
  • one complete action each time, so perfective

Yes. Позавтракать is the perfective partner of завтракать.

• завтракать = imperfective
• позавтракать = perfective

In many verbs of eating or spending time, по- helps form a perfective verb meaning the action is done as a complete event.

So:

• завтракать = to have breakfast
• позавтракать = to eat breakfast / have breakfast completely, as one finished action

It does not mean a little breakfast here. It mainly marks completion.

Because дома means at home, while в доме means in the house/building.

• дома = at home
• в доме = in the house

In this sentence, the natural idea is at home, not physically inside a particular building as opposed to outside it.

So:

• Я завтракаю дома. = I eat breakfast at home.
• Я завтракаю в доме. = I eat breakfast in the house.
  This sounds more literal and less natural in this context.

Yes, often it can.

Both are possible:

• Если я встаю рано, я успеваю позавтракать дома.
• Если я встаю рано, успеваю позавтракать дома.

Including the second я is perfectly normal. It can make the structure clearer or slightly more balanced. Russian often repeats the subject in the main clause, especially in careful or neutral speech.

Yes. Russian word order is flexible, though the original version is the most neutral.

Possible variations:

• Если я рано встаю, я успеваю позавтракать дома.
• Я успеваю позавтракать дома, если я встаю рано.

The meaning stays similar, but the emphasis changes a bit.

• Если я встаю рано... focuses first on the condition.
• Я успеваю... если... starts with the result.
• рано can move around, but it usually stays close to встаю.

Grammatically, the verbs are in the present tense, but the meaning is general/habitual.

So it means something like:

• Whenever I get up early, I manage to have breakfast at home.

It is not just about what is happening right now. It describes a regular pattern.

If you wanted a specific future meaning, Russian would more likely use perfective future forms:

• Если я встану рано, я успею позавтракать дома.
• If I get up early, I’ll manage to have breakfast at home.

Yes, and it would be very close in meaning.

• Если я встаю рано... = If/when I get up early...
• Когда я встаю рано... = When I get up early...

The difference is:

• если presents it as a condition
• когда presents it more directly as a repeated time situation

In many everyday contexts, both work.
But if you want to emphasize under that condition, если is a very natural choice.

Because the subject is я = I.

So the forms are:

• я встаю = I get up
• я успеваю = I manage / have time
• позавтракать = infinitive, so it does not change for person

These verb endings help identify the subject even if я is omitted.

They are:

• встаю → вставать / встать
• успеваю → успевать / успеть
• позавтракать → позавтракать (perfective), paired with завтракать

This is useful because Russian dictionaries usually list verbs in the infinitive.

Also note the aspect pairs:

• вставать / встать = to get up
• успевать / успеть = to manage, to have time
• завтракать / позавтракать = to have breakfast

A natural future version would be:

• Если я встану рано, я успею позавтракать дома.

Why?

• встану = I get up / will get up on a specific future occasion
• успею = I will manage
• позавтракать stays perfective because it is still a completed action

So the original sentence is general/habitual, while this version is specific future.

Either can work. The exact English translation depends on context.

• успеваю can mean I manage to
• It can also mean I have time to

In this sentence, both are natural:

• If I get up early, I manage to have breakfast at home.
• If I get up early, I have time to have breakfast at home.

The Russian verb often includes both ideas: there is enough time, and as a result the action gets done.

It is an adverb here, because it describes how/when the action happens:

• встаю рано = I get up early

It modifies the verb встаю, not a noun.

Compare:

• ранний завтрак = an early breakfast
  
  • ранний is an adjective
• встаю рано = I get up early
  
  • рано is an adverb