Learn Hardcore Russian: Мы поздравили друга и подарили ему книгу. - We congratulated a friend and gave him a book.

Ему is dative (to him), which you need for the recipient of a gift. Его is accusative/genitive (him/his) and would be wrong here. After подарить, the recipient is in the dative: подарили ему книгу.

Why is книгу used instead of книга?

Книгу is the accusative singular of the feminine noun книга. Feminine nouns in -а/-я change to -у/-ю in the accusative when they are direct objects: книга → книгу, машина → машину, идея → идею.

What case pattern does подарить take?

Подарить governs:

Recipient: dative (кому?)
Gift: accusative (что?) So: подарили ему (кому?) книгу (что?). Word order can be подарили ему книгу or подарили книгу ему.

Do I need to add the occasion with поздравить?

Often yes. The common pattern is поздравить кого с чем (with instrumental after с):

поздравили друга с днём рождения
поздравили друга с победой Your sentence is fine without it if the occasion is understood from context.

Are both verbs perfective, and why?

Yes: поздравили (from поздравить) and подарили (from подарить) are perfective past. Perfective presents completed, one-time actions. Imperfective would be поздравляли, дарили (process/habit).

Can I mix aspects like поздравляли друга и подарили ему книгу?

Yes, but the nuance changes. Поздравляли suggests an ongoing/habitual action, while подарили is a single completed action. It could mean you were in the process of congratulating and then gave the book, or that you used to congratulate him and once gave a book—context decides.

How flexible is the word order around ему and книгу?

Quite flexible:

Neutral: подарили ему книгу
Also possible: подарили книгу ему
With emphasis: Ему подарили книгу, Книгу ему подарили, Книгу мы подарили ему Pronouns like ему are often placed earlier; moving elements changes emphasis, not core meaning.

Why is there no comma before и?

It’s one subject (мы) with two predicates (поздравили, подарили), so no comma is needed. If you insert a phrase like а потом, you add a comma: Мы поздравили друга, а потом подарили ему книгу.

Could I repeat the noun instead of using the pronoun?

Grammatically yes: Мы поздравили друга и подарили другу книгу, but it’s repetitive. Using ему is more natural. Don’t use его here; его is not the recipient case. Note: подарили его книгу would mean “gave his book,” which is different.

How would this change if the friend is female?

Use the feminine noun and pronoun:

Мы поздравили подругу и подарили ей книгу. Here подругу is accusative (fem.), and ей is dative (to her).

Can I omit the subject мы?

Possible in context: Поздравили друга и подарили ему книгу. However, in the past tense the verb shows number but not person, so without мы it could be read as они (they). Keep мы if clarity matters.

Does the sentence imply the order of actions?

Not strictly, but narrative order usually matches mention order, so readers will naturally infer “congratulated, then gave.” To be explicit, use сначала … потом: Мы сначала поздравили друга, потом подарили ему книгу.

What’s the difference between подарить and дать?

Подарить = to give as a gift (special occasion, no return expected).
Дать = to give/hand/lend in a general sense. Both take dative for the recipient, but подарить clearly signals a present: подарили учителю книгу vs дали учителю книгу (just handed or lent a book).

How do I pronounce/stress the key words?

Stress marks: Мы поздрáвили дру́га и подари́ли ему́ кни́гу.

поздрáвили (stress on -ра-)
дру́га (on -ру-)
подари́ли (on -ри́-)
ему́ (on -у́)
кни́гу (on -кни́-)

Can I use а instead of и?

Usually no. А contrasts or opposes clauses (“while/but”), so Мы поздравили друга, а подарили ему книгу sounds contrastive or odd. If you want sequence, use и or а потом: Мы поздравили друга, а потом подарили ему книгу.