Pitkä välilasku on helpompi, jos löytää rauhallisen kahvilan.

Yes. Välilasku is a very normal travel word for layover or stopover.

Literally, it is a compound:

• väli = interval, in-between
• lasku = landing

So the literal idea is something like an in-between landing.

In real usage, though, you should just understand välilasku as layover / stopover.

Because pitkä välilasku is the subject of the sentence, so it is in the nominative form.

• pitkä = long
• välilasku = layover

In Finnish, the basic dictionary form is used for the subject:

• Pitkä välilasku on helpompi. = A long layover is easier.

If it were in another grammatical role, the form could change:

• pitkän välilaskun aikana = during a long layover

So here, nominative is used because it is the thing being talked about.

Because helpompi is the comparative form of helppo.

• helppo = easy
• helpompi = easier

So:

• Pitkä välilasku on helpompi = A long layover is easier

Finnish often uses the comparative even when the second thing being compared is not stated explicitly. Here the comparison is understood as something like:

• easier than it would otherwise be
• easier than a layover without a quiet café
• easier to get through

So the sentence is not saying a long layover is simply easy. It is saying it becomes easier under that condition.

This is a very common Finnish pattern called the zero person.

Jos löytää rauhallisen kahvilan literally looks like:

• if finds a quiet café

But in natural English, it means:

• if you find a quiet café
• if one finds a quiet café
• if someone finds a quiet café

Finnish often leaves the subject unspoken when the meaning is people in general or anyone in that situation.

So this sentence is making a general statement, not speaking to one specific person.

Yes, absolutely.

• jos löytää rauhallisen kahvilan = general, impersonal: if you/one/someone finds a quiet café
• jos löydät rauhallisen kahvilan = directly addressed to you

The original sentence sounds more general and less personal. It is like saying:

• A long layover is easier if you can find a quiet café

Using löydät would sound more like you are talking to one particular person.

Because rauhallinen is an adjective modifying kahvila, and in Finnish adjectives usually agree with the noun they describe.

So:

• kahvila → kahvilan
• rauhallinen → rauhallisen

This is normal Finnish adjective agreement.

Compare:

• rauhallinen kahvila = a quiet/calm café
• rauhallisen kahvilan = of a quiet/calm café / a quiet/calm café as a total object form here

The important point is that the adjective follows the noun’s case.

Because kahvilan is the total object form here.

With a verb like löytää (to find), Finnish usually uses the total object when the action is seen as completed and successful:

• löytää kahvilan = find a café

This is why you get:

• rauhallisen kahvilan

By contrast, kahvilaa would be partitive, which often suggests something incomplete, ongoing, or indefinite. For example:

• etsii rauhallista kahvilaa = is looking for a quiet café
• ei löydä rauhallista kahvilaa = does not find a quiet café

So:

• löytää rauhallisen kahvilan = successfully finds one

Both words can relate to quietness, but they are not exactly the same.

• rauhallinen = calm, peaceful, relaxed
• hiljainen = quiet, silent, not noisy

A rauhallinen kahvila suggests a café with a calm atmosphere, a place where it is easier to rest or wait.

A hiljainen kahvila would focus more directly on the lack of noise.

In this sentence, rauhallinen sounds very natural because the idea is not just silence, but a comfortable, peaceful place during a layover.

Because Finnish normally uses a comma between a main clause and a subordinate clause.

Here:

• Pitkä välilasku on helpompi = main clause
• jos löytää rauhallisen kahvilan = subordinate clause

So the comma is standard Finnish punctuation:

• Pitkä välilasku on helpompi, jos löytää rauhallisen kahvilan.

This is different from English, where a following if-clause often has no comma:

• A long layover is easier if you find a quiet café.

So this comma is something English speakers often need to get used to in Finnish.

Yes. Finnish word order is fairly flexible.

You could also say:

• Jos löytää rauhallisen kahvilan, pitkä välilasku on helpompi.

That means the same thing:

• If you find a quiet café, a long layover is easier.

The original version starts with the main point:

• Pitkä välilasku on helpompi...

The alternative starts with the condition:

• Jos löytää rauhallisen kahvilan...

Both are correct; the difference is mostly about emphasis and flow.

Because helpompi is the correct form when it is a predicate adjective describing a singular nominative subject.

Here the subject is:

• pitkä välilasku

So the structure is:

• Pitkä välilasku on helpompi.

By contrast, helpompaa often appears in different kinds of structures, for example:

• On helpompaa odottaa kahvilassa. = It is easier to wait in a café.

In that type of sentence, there is no concrete nominative subject like pitkä välilasku. That is why the form changes.

So in your sentence, helpompi is the right choice.