"Мне не нравится этот стул."
Translation:I do not like this chair.
No (as szeraja_zhaba explained), but 'столъ' used to mean a chair/altar in Church Slavonic, so in some sense yes.
I find it weird how стол has appeared so much earlier than стул when they are so similar, it's a learning tactic for when you master some words they show us the similar ones so we can learn they easily or what is it?
Actually it's been shown that people are much more likely to confuse words or mix them up if they learn similar sounding or meaning ones at the same time. If it's intentional on their part it's to help you learn better!
Have you seen the guide to loving and liking by olimo: https://www.duolingo.com/comment/11754722 ?
If you see that chair often, and you don't like sitting on it every time, you can use both. However, if you see it for the first time and don't like it 'at first sight', then you can only use «нравиться».
No, that would be «табуре́тка» or (more formally) «табуре́т».
«Стул» can only be translated as «stool» in medical sense.
In Spanish we actually also have the word "taburete" for "stool"! It's fascinating to see how languages are somehow related, no matter how distant some of them are now.
[этот стул] is one construction. Both parts of it have the same function in the sentence. [это] (есть) [стул] is two different phrases that have two different functions in the sentence (subject and predicative) separated by the verb. The tricky part is that there's usually no verb in these kinds of sentences, so they can be hard to recognize.