Definitely. It's always recommended to use more than one source when learning anything

I dont know if this is correct, but i always assumed it was to differenciate between 炬燵 (こたつ, kotatsu) and a western style table

Because they do not used table in ancient time perhaps

机（つくえ）also means table in Japanese. Either one works

Fun fact that they actually have (机/つくえ), but system consider this answer as mistake (well, at least made it for me) and asks specifically for テーブル. I would assume that it's because of table/desk thing, but... honestly, for me personally table is just a table, since I'm not native English.

Because Japanese's culture is different. They probably didn't use tables and if they did they were the low down ones. You can do a little research on their culture too and figure it out.

There is, 机(つくえ). For some weird reason, they preferred not to use it, and not even put this along the correct answers.

There is a word for it, however it is for Japanese style vs Western style. The same thing can be seen in doors. ドア vs 扉 (pronounced とびら)。The 扉 is typically a sliding style door, such as in a home or on a train.

Yep, it basically just doubles the sound of the vowel before it, kind of like when っ/ッ doubles the consonant after it. Double vowels are represented by the symbol on top of them (as in ō) in romaji, btw

1 will not occur between katakana.

There is a Japanese word, actually - 机/つくえ. But system consider it as wrong answer, don't know why.

but do you have a プールテーブル？

Nope, for this you would like to use Japanese word, 表 「ひょう」.

the small tsu (っ and ッ) is used to signify a double consonant in a word. you don’t literally pronounce the “tsu” sound; it’s more like an accent mark in which you sort of hold your breath and pronounce the syllable sharply.

for example: 「いた」 is pronounced eetah and means “was somewhere” but 「いった」 is pronounced eetta and is a completely different word, meaning “has said” or "was said".

some other examples:

「きっぷ」 = kippu (ticket)

「ほっかいどう」 = hokkaidō (北海道)

「にっさん」 = nissan (日産)

you pronounce words with the small tsu in katakana (which is used to spell foreign words or names in japanese) the same way you do in hiragana. for example:

「ワッフル」 = waffuru (waffle)

「ベッティ」 = betti (Betty)

「ペッパーコーン」 = peppaahkōhn (peppercorn)

you also see the small tsu used onomatopoetically at the end of words or sentences sometimes to convey emotion, or even a gasp, shriek, or harsh tone. you still use it the same way, holding your breath and sharpening the pronunciation of the syllable:

「アッ！」 = ah!

「ぎゃっ！」 = gya! (yikes!)

「こら」 means something like “yo!” but 「こらっ！」 gives the expression more urgency and a little punch to mean something closer to, “yo, careful!”

.

the long dash (ー) symbol in katakana is sort of the opposite of the small tsu. instead of holding your breath and sharpening the syllable, you elongate it. just think of it like a morse code dash (sounded longer) and the small tsu as a morse code dot (a staccato) and you'll be fine.

since the long dash is almost always used in katakana (not hiragana or kanji) it’s to help pronounce non-japanese words. for example, 「ビル」 is pronounced biru and people might think you’re saying “Bill”. but 「ビール」 is pronounced biiiru and helps the listener or reader know that you mean “beer”.

likewise, the ー symbol is used to spell words like 「ジュース」 (jyuusu or juice) and 「アイスクリーム」 (aisu kuriimu or ice cream).

sometimes long dashes may be strung together to convey meaning and dramatic effect. 「アー」 means “ahh” but 「アーーーー」 would mean “ahhhhhhhh”. you get the idea.

you might see the symbol used with hiragana on occasion as a shortcut, like 「えー」 instead of 「ええ」, and 「おかーさん」 instead of 「おかあさん」 (お母さん) but i believe it’s informal and more like written slang rather than proper japanese.

you might also see a wavy long dash (〜) in japanese adverts, online chats, comics (manga), and other pop media. it’s just a playful or stylistic version of the regular long dash, and more written slang than proper japanese - it wouldn't be used in a business or legal document or a formal letter, for example.

sometimes the wavy long dash is used to signify a playful or wavering voice. so, 「ヘイ〜」 is like “heyyyyy”, perhaps said lightheartedly. the reader would know the meaning by the context of the discussion.

hope this all makes sense! sorry for the long-winded explanations.