Translation:This bread tastes good but that bread tastes bad.
Since tasty means savory or delicious, if you replace the suffix "-y" with the suffix "-less", it now is tasteless meaning not tasty. They made this word so we don't have to use two words to describe something that is not tasty. However, not tasty would work if you it's okay for you.
It is used in that way. However that usage does not mean it doesn't also mean what the commenter above you said. It is a word with more than one meaning. In this case, it means something does not have good flavour. Context is a powerful thing. I doubt very much that bread can be crass or ill-considered.
You are, of course, correct, but in my experience "tasteless" is rarely used to describe something lacking flavor, which I think would be the most appropriate definition when applied to something ingested. Rather than a "bad" flavor, it would connote no flavor or a very bland taste. The Korean "맛없다" though translating literally to "no taste" is generally used to describe something that tastes bad. Often times a very literal translation does not really convey the intended thought.
Perhaps consider the words "flavorful" versus "flavorless". Those are almost exclusively used regarding food in English. Other languages use versions of the word flavor more often than taste. "Taste" is usually only an action verb in most languages I've studied. "In poor taste" is an English idiom, for example.
So, unfortunately, 저 doesn't mean "my," it means "I/me."
But thankfully, the Korean language has a hack, which might be a bit visually confusing at first. You can shorten 저의 into 제 (as well as 나의 into 내).
What's happening here is they're combining both final vowels, and creating the "ae" diphthong from it, so "ㅓ and ㅣ in 저의 become ㅔ" and "ㅏ and ㅣ in 나의 become ㅐ."
This way it's less cumbersome and a little more natural to say/read, though both I'd say are used almost equally.
저 has 2 meanings. It either means 'I'/'me' or it means 'that' when referring to an object far from both the speaker and the listener. In this sentence it is the latter and means 'that'.
My, as another commenter said is either '저의' or in short form '제'. They explained why very well in their comment.
No, it's not. Even in English that sentence is incorrect. To be more clear, you've written a run on sentence in English- you need a conjunction such as "and," "but," etc.
For this sentence, it uses the "~지만" grammatical principle, which would primarily translate to "but" or "however."
Just like in English, although you specify a topic in the initial clause, the second clause has no topic in your case. So you could be talking about anything, like milk, meat, candy, etc. I think the only way to get out of it is if you were actually saying the sentence and physically pointing at the other bread.