Хотя салями и солёная, я иногда делаю тост с салями и сыром.

Here и is not the usual and.

In this pattern, хотя ... и ... means something like:

• although ...
• even though ...
• while it is true that ...

So Хотя салями и солёная means Although salami is salty.

The и adds a concessive nuance and makes the contrast sound more natural. You can think of it as reinforcing the idea: although salami is indeed salty...

You will often see:

• Хотя он и устал, он продолжал работать.
  Although he was tired, he kept working.

Салями is an indeclinable loanword, and in standard Russian it is usually treated as feminine.

That is why the adjective is feminine:

• солёная = feminine
• not солёный = masculine

A helpful way to remember this is that салями is a type of колбаса, and колбаса is feminine.

So:

• салями солёная
• вкусная салями
• эта салями

Because салями is indeclinable.

Normally, after с meaning with, Russian uses the instrumental case. Many nouns change form:

• сыр → с сыром
• друг → с другом

But салями stays the same in every case:

• салями
• о салями
• без салями
• с салями

So even though с requires the instrumental, the word itself does not change.

Because сыр is a regular declinable noun, while салями is indeclinable.

After с = with, both nouns are grammatically in the instrumental case:

• с салями
• с сыром

But only сыр shows a visible case ending:

• сыр → сыром

Салями is also instrumental here, but its form does not change.

Russian usually omits the present-tense form of to be.

So:

• Салями солёная. = Salami is salty.
• literally: Salami salty.

This is completely normal in Russian.

The adjective солёная acts as the predicate, and the meaning is is understood automatically.

Because here the adjective is in the nominative feminine singular form, agreeing with салями.

In a sentence like Салями солёная, the predicate adjective is normally nominative in modern standard Russian.

So:

• салями = feminine singular
• солёная = feminine singular nominative

A form like солёной would not fit this sentence.

Because Хотя introduces a subordinate clause:

• Хотя салями и солёная, = subordinate concessive clause
• я иногда делаю тост с салями и сыром. = main clause

Russian separates these with a comma, just as English often does with Although..., ...

Yes. Делать is often used in everyday Russian for preparing simple food items, especially something quick or informal.

So делаю тост sounds like:

• I make toast
• I fix myself some toast

You could also hear:

• готовлю тост
• делаю бутерброд
• готовлю бутерброды

But делаю is perfectly natural in casual speech.

In this sentence, тост means toast as food, not a speech or raised-glass toast.

Russian тост can mean both:

• a toast at a celebration
• a piece of toast / toasted bread

The context makes it clear here, because of с салями и сыром.

Russian often uses one preposition for both coordinated nouns when the meaning is shared:

• с салями и сыром = with salami and cheese

This is the most neutral version.

You can say с салями и с сыром, but repeating the preposition is usually for emphasis, rhythm, or clarity. In ordinary speech, one с is enough.

Yes. Russian word order is flexible.

These are all possible:

• Я иногда делаю тост с салями и сыром.
• Иногда я делаю тост с салями и сыром.
• Я делаю иногда тост с салями и сыром.

The first two are the most natural here. The version in your sentence sounds neutral and standard.

Yes, it could.

• Хотя салями солёная, я иногда делаю тост с салями и сыром.

This is still grammatical and understandable.

Adding и makes the concessive relationship sound a little more idiomatic and expressive:

• Хотя салями и солёная...
  Although salami is salty...

So the и is common and natural, but not absolutely required.