Gelinle damat salona girer girmez herkes alkışladı.

Here -le is the attached form of ile. Its basic meaning is with, but when two nouns are paired, it can also work like and.

So:

• gelinle damat = the bride and groom
• gelin ve damat would also be correct

In this sentence, gelinle damat sounds very natural and compact.

Because salona uses the dative case and shows movement into / toward a place.

• salon = hall / room / salon
• salona girmek = to enter the hall
• salonda = in the hall
• salondan = from/out of the hall

So salona girer girmez means as soon as they entered the hall.

Girer girmez is a very common Turkish structure meaning:

• as soon as ...
• the moment ...
• no sooner ... than ...

It is built by repeating the same verb:

• girer = enters
• girmez = does not enter

But you should not translate it literally as enter-not-enter. As a whole, it is an idiomatic pattern meaning immediately upon entering.

Other examples:

• Eve gelir gelmez beni aradı. = He called me as soon as he got home.
• Haberi duyar duymaz çıktı. = She left as soon as she heard the news.

In girer girmez, the form is part of a fixed adverbial pattern, so it does not set the main time of the sentence by itself.

The real tense of the whole sentence comes from the main verb:

• alkışladı = applauded

So the sentence is past overall:

• Gelinle damat salona girer girmez herkes alkışladı.
• As soon as the bride and groom entered the hall, everyone applauded.

You can use the same girer girmez structure with different main tenses too:

• ... herkes alkışlar. = everyone applauds
• ... herkes alkışlayacak. = everyone will applaud

That is normal in Turkish.

Even when the subject is plural, Turkish often uses the 3rd person singular verb form, especially when:

• the plural subject is already clearly stated
• the verb is inside a subordinate/adverbial structure like girer girmez

So gelinle damat salona girer girmez is the natural form.

Using girerler girmez would sound unusual here.

Because herkes is grammatically treated as singular in Turkish, even though it means everyone.

So:

• herkes alkışladı = correct
• herkes alkışladılar = not standard

This is similar to how English says everyone is, not everyone are.

The object is simply understood from context.

In this sentence, the natural understanding is:

• everyone applauded the bride and groom

Turkish often leaves an object unstated when it is obvious.

So these are both possible:

• Herkes alkışladı. = Everyone applauded.
• Herkes onları alkışladı. = Everyone applauded them.

The version without onları is completely normal here.

Yes, but the meaning changes slightly.

• salona girince = when / once they entered the hall
• salona girer girmez = as soon as they entered the hall

So girer girmez is more immediate. It emphasizes that the applause happened right away, with almost no delay.

Compare:

• Gelinle damat salona girince herkes alkışladı.
  = When the bride and groom entered the hall, everyone applauded.

• Gelinle damat salona girer girmez herkes alkışladı.
  = The moment the bride and groom entered the hall, everyone applauded.

No, Turkish word order is flexible, but this sentence has a very natural neutral order.

• Gelinle damat salona girer girmez herkes alkışladı.

This presents the background event first, then the main action.

You can move parts around for emphasis, but the tone changes. For example:

• Herkes, gelinle damat salona girer girmez alkışladı.
• Gelinle damat salona girer girmez, herkes alkışladı.

These are still understandable, but the original version is smooth and standard.

Not exactly.

In Turkish, salon can mean several things depending on context, such as:

• a hall
• a large room
• a living room
• an event or reception hall

In this wedding sentence, salon most likely means the hall / reception hall / ballroom where the event is taking place.

So salona girmek here is best understood as to enter the hall.

Yes. It sounds very natural and story-like in Turkish.

The structure:

• [background event] + girer girmez + [main event]

is a common way to describe something happening instantly after something else.

So the sentence feels vivid and smooth, almost like:

• The moment the bride and groom walked into the hall, everyone applauded.

It is a very typical and useful pattern to learn.