Only so much as Spanish is a poetic language. Saber means both to know and to taste. And in English when we talk about savouring food the word savour comes to us from French (I think) and probably originated in Latin. Unless found in a poetic context it is a straight forward Spanish translation of taste.
Nope, here bien must be used. Bien is used to qualify verbs (it's an adverb) and is more like the English word well. Buen/@ is used to describe nouns (La miel es buena).
The simple way to remember it is that buen/@ is used after ser, and bien is used after estar and most other verbs. This may not be true 100% of the time of course but it's a good guideline.
No really good reason. IMO, just that sometimes it's probably a big job to keep up with all the possible concatenations of all the sentences. I, too, was frustrated in the beginning, but frustration is counter productive to learning, so I took to just going for the safest answers, figuring that my translation to English was less important than the learning process. Zen. ;-|
I assume you understand that ese eso and esa are 'that', adding the 't' makes it this. Then, unlike most verbs and nouns, the endings are slightly different. Esa is still feminine, but for this set of words, ese is masculine, eso is neuter. It is still very difficult for me to understand exactly when you can or should use the neutered form, but watch the noun for usage of the masc/fem. Ese libro, esa mujer.