Learn Hardcore Russian: Она обязательно придёт, если ей хватит времени. - She will definitely come if she has enough time.

It means definitely/without fail/surely; it expresses the speaker’s strong confidence.
It can also mean obligatorily (you must) in other contexts: Обязательно принесите паспорт.
Close synonyms for this use: непременно (a bit formal), точно (colloquial “for sure”), наверняка (very likely, slightly less categorical than обязательно).

Why is придёт used—what tense/aspect is it? Could I say будет приходить or приходит?

Придёт is the simple future of the perfective verb прийти. In Russian, perfective “present” forms refer to the future.
It conveys a single, completed arrival.
Будет приходить (imperfective future) means will come repeatedly/habitually.
Приходит (present) expresses a habitual present, not a single future event.

Is придёт the same as приедет?

Придёт typically implies coming on foot or simply arriving at a place; приедет implies arriving by vehicle.
If the mode of arrival is irrelevant, either can be acceptable depending on context.

Why is it ей and not её?

Ей is dative (to/for her) and fits the pattern with хватать/хватить: кому хватает/хватит чего (to/for whom something is enough).
Её is genitive/accusative. It appears after у to mark possession: у неё.

Can I say у неё instead of ей?

Why is времени in the genitive?

With хватить/хватать, the thing that suffices takes the genitive: кому хватает/хватит чего.
This is a partitive-genitive use common with quantities. Note the irregular genitive singular of время is времени.

Could I say если у неё хватит времени or если у неё будет время? Are they different?

Both are correct:
- Если у неё хватит времени stresses sufficiency for the task.
- Если у неё будет время means she will have (some) time available, without emphasizing “enough.”
Avoid если ей будет время; with быть to show possession, use у неё, not dative.

Can I start with the if-clause, and what about punctuation?

Why does the if-clause use a future form? In English we’d say “if she has enough time.”

For real future conditions, Russian typically uses future forms in the если-clause: если ей хватит (future of perfective хватить).
English uses present in the if-clause; the mismatch is normal.

How do I make it negative?

Can обязательно move, and does that change meaning?

Common placements:
- Она обязательно придёт... (neutral, very common)
- Она придёт обязательно... (slight emphasis on the act of coming)
- Обязательно она придёт... (stronger, more expressive emphasis)
The core meaning stays; it’s about emphasis and rhythm.

Pronunciation and stress?

Онá обязáтельно придёт, éсли ей хвáтит врéмени.
Tips:
- придёт has ё, which is always stressed; it may be printed as придет but still pronounced придёт.
- хвáтит stress on the first syllable.
- врéмени stress on the first syllable.

Why is it spelled придёт and not прийдёт?

The infinitive is прийти, but in conjugation the й drops: приду, придёшь, придёт, придём, придёте, придут.
Прийдёт is a common misspelling; the correct form is придёт.

What construction is ей хватит времени?

It’s an impersonal quantity construction:
- Pattern: кому хватит/хватает чего (на что).
- Examples: Мне хватит времени на обед. Ему не хватает денег.
You can omit the experiencer if clear: Если хватит времени, ... (if there’s enough time).

Can I replace хватит with достаточно?

Yes: Если у неё будет достаточно времени, она обязательно придёт.
Also possible: Ей будет достаточно времени. This sounds a bit more neutral/formal.