"Is this a menu?"
It is unfortunate for beginners of Japanese, but the English sound "this" has two quite different meanings. The one that corresponds to この has to be followed by a noun, "this [thing/person, specified]," これ is a noun, and already means "this thing" all by itself and will likely be followed by a particle は、が、に、も、で, etc. This of course applies to それ/その and あれ/あの as well.
I always thought of it slightly differently. You are correct, and I'm probably wrong, but the way I think about it helps me remember it all a bit better.
I see the こ as an abbreviation of ここ. ここ means "here", and when I see この I think of it as ここの where the の indicates possession. For instance: I see "this book" as "the book I have here" or "the book here". Therefore I would translate it to ここの本, which I can shorten to この本.
I do this with other similar words as well. こち (to me) is short forここのみち - "the road here", or "this way". Maybe this one works better for me since I'm Dutch, and the Dutch word for "road" ("weg") has a double meaning. I can ask "waar kom jij weg", which means "where are you from".
Anyways, back on topic. I see これ as two words as well. In this case I read it as こ = 'this' and れ = 'thing'.
(I really hope this makes sense..)
There's nothing wrong with it; 「これはメニューですか」 and 「メニューはこれですか」 are largely interchangeable in most circumstances, but their nuances are subtly different.
With 「これはメニューですか」, これ is the focus of the sentence, so you're asking if "this thing" that you are holding or pointing to is a menu (and not something else). That is, "Is this a/the menu?" As such, I presume you're more likely to hear and use this sentence.
With 「メニューはこれですか」, メニュー is the focus. So this time you're asking if the menu is "this thing" that you're holding or pointing to (and not some other thing). That is, "Is the menu this one?"
It would mean "this is a 'me 2 rū'".
Somehow you've managed to write a katakana 'me', then the kanji for 2, and then the katakana 'ru' instead of the little 'yu'.
There are the kanji for 2 and the katakana 'ni' respectively: 二ニ.
When they're side by side it's easier to spot the difference in size.
Based on your other comment you made a month ago, I think you're misinterpreting how これ vs この is used. Both mean "this" but これ is a noun, while この is an adjective, it requires a noun immediately afterwards for it to work. The difference isn't whether or not there's a noun in the sentence at all, the difference is whether or not the noun is immediately (ie, not even with another particle) after これ or この.
I suspect you've slightly misinterpreted whatever told you that you use これ instead of この when there's no noun in the sentence. You can use これ when there's no other noun but that's not a requirement. It just means "this thing", while この does require there to be another noun immediately after it for it to work though.
The noun isn't being mentioned DIRECTLY after, but is mentioned in the sentence itself. So この (menu/object) (rest of the sentence) is correct when trying to say "this menu..." And これ は (rest of the sentence which mentions you are talking about a menu) is correct when trying to say this thing is... (something about menu's) So is this a menu would be an example to use kore