Why is it "To" and not "Ta"? I assume "slova" are neuter. So if I would say "Ta slova" it would be correct, right? Then why in this sentence it is "To"?
"To je" and "to jsou" is a phrase to identify objects/people/even something imaginary like information. If you did not use "to", but only said Jsou slova., it would mean they exist.
To jsou ta slova. would require definite article in English, so you would mean some specific words known from previous context. Those are the words.
For the two phrases gender of nouns does not matter. You only use je/jsou depending if the noun is in sg or plural.
In English you also have two different sentences - "Those words are good" isn't the same as "Those are good words". It's the same thing here. If you wanted to say "Those words are good" it would be "Ty slova jsou dobra".
No, it's neuter (slovo) and uses the pattern "město" to be declined. The plural nominative is "města -> slova".