Pregledat ću dokumentaciju što pažljivije prije nego što predam zahtjev.

Both patterns are possible in Croatian, but they follow different word-order rules.

• pregledat ću = the short infinitive
  • the clitic ću
• ću pregledati would normally only appear if something else comes first, for example:
  • Sutra ću pregledati dokumentaciju.
  • Ja ću pregledati dokumentaciju.

In Croatian, clitics like ću usually take the second position in the clause. If the verb itself comes first, Croatian often uses the shortened infinitive:

• pregledati → pregledat
• so: Pregledat ću...

So this sentence is a very normal and natural way to say it.

Ću is the 1st person singular form of the auxiliary verb used to make the future tense.

The full set is:

• ću = I will
• ćeš = you will
• će = he/she/it will
• ćemo = we will
• ćete = you (plural/formal) will
• će = they will

So:

• Pregledat ću = I will review / I’ll review

Because Croatian often uses a short infinitive in the future tense when the infinitive comes directly before the clitic auxiliary.

• full infinitive: pregledati
• short infinitive: pregledat

So these are related:

• Pregledat ću dokumentaciju.
• Ja ću pregledati dokumentaciju.

They both mean the same thing. The difference is mainly grammatical position and style, not meaning.

Because dokumentaciju is in the accusative case, which is used here for the direct object of the verb pregledati.

• nominative: dokumentacija
• accusative: dokumentaciju

Since the speaker is reviewing the documentation, the noun is the thing directly affected by the action, so accusative is required.

Not exactly. Dokumentacija usually means documentation, meaning a set of documents, paperwork, records, or supporting materials treated as a whole.

So:

• dokumentacija = documentation / paperwork
• dokumenti = documents

In this sentence, dokumentaciju suggests the speaker is reviewing the whole body of paperwork, not just a few separate documents.

Literally, it is something like as more carefully as possible, but in natural English it means:

• as carefully as possible
• as carefully as I can

Here is how it works:

• pažljivo = carefully
• pažljivije = more carefully
• što pažljivije = as carefully as possible / as carefully as one can

This is a common Croatian pattern: što + comparative to mean as ... as possible.

Examples:

• što prije = as soon as possible
• što bolje = as well as possible
• što pažljivije = as carefully as possible

Because Croatian uses the comparative here after što.

• pažljivo = carefully
• pažljivije = more carefully

The phrase što pažljivije is an idiomatic structure meaning as carefully as possible, not simply carefully.

So:

• Pregledat ću dokumentaciju pažljivo = I will review the documentation carefully.
• Pregledat ću dokumentaciju što pažljivije = I will review the documentation as carefully as possible.

The second one sounds stronger and more deliberate.

Prije nego što means before or more literally before that and introduces a subordinate clause.

So:

• prije nego što predam zahtjev = before I submit the application/request

Croatian often uses:

• prije nego što + verb

This is a very common structure.

Examples:

• Nazvat ću te prije nego što krenem. = I’ll call you before I leave.
• Razmislit ću prije nego što odgovorim. = I’ll think before I answer.

This is one of the most important things for learners to notice.

After conjunctions like prije nego što, Croatian often uses the present tense form of a perfective verb to refer to a future completed action.

Here:

• predati = to submit / hand in
• predam = present-tense form of a perfective verb

Even though it looks like present tense, in this kind of clause it refers to the future:

• prije nego što predam zahtjev = before I submit the application

This is normal Croatian grammar, not a mistake.

Formally, yes: predam is a present-tense form. But because predati is a perfective verb, its present form often has a future meaning in subordinate clauses or in certain contexts.

That is why Croatian can say:

• kad dođem = when I come / when I arrive
• prije nego što predam = before I submit
• nakon što završim = after I finish

English usually uses a present form too in these time clauses:

• before I submit
• not usually before I will submit

So the Croatian structure is actually quite parallel to English in this case.

Because zahtjev is the direct object of predam, so it is in the accusative case. For many masculine inanimate nouns, the accusative singular is the same as the nominative singular.

So:

• nominative: zahtjev
• accusative: zahtjev

That is why the form does not change here.

Zahtjev usually means request, application, or formal submission, depending on context.

In bureaucratic or administrative contexts, predati zahtjev often means:

• to submit an application
• to file a request
• to hand in a formal request

So in this sentence, it likely refers to some kind of official application or request form.

Because Croatian often drops subject pronouns when they are not needed. The verb ending already shows who the subject is.

• pregledat ću clearly means I will review
• predam also fits with I

So ja is unnecessary unless you want emphasis or contrast.

Compare:

• Pregledat ću dokumentaciju. = I will review the documentation.
• Ja ću pregledati dokumentaciju. = I will review the documentation.
  This can sound more emphatic, like contrasting with someone else.

Yes, Croatian word order is fairly flexible, but not completely free. Clitics such as ću still have placement rules.

This sentence could be rearranged depending on emphasis, for example:

• Dokumentaciju ću pregledati što pažljivije prije nego što predam zahtjev.
• Prije nego što predam zahtjev, pregledat ću dokumentaciju što pažljivije.

These versions are all natural, but the emphasis shifts:

• starting with dokumentaciju emphasizes what will be reviewed
• starting with prije nego što... emphasizes the time sequence

So the original sentence is neutral and natural, but not the only possible wording.

Yes. Što je moguće pažljivije means almost the same thing and is a bit more explicit:

• što pažljivije
• što je moguće pažljivije

Both mean as carefully as possible.

The shorter version in your sentence is very common and natural.

It sounds neutral to slightly formal, mostly because of the vocabulary:

• dokumentacija
• zahtjev
• predati zahtjev

These words are common in administrative, professional, or official contexts. Grammatically, though, the sentence is standard and normal Croatian, not especially stiff or unnatural.