1) 是 is necessary for the sentence. It is not there to shorten "喜欢". They are different in terms of grammatical structure. 2)Yes. They are interchangeable.

1) As for "尤其”, "是“ is not necessary, but it could make the sentence more fluent. 2) ”特别“ and "尤其”, in most cases, are interchangeable. But as for “特别”, “是” cannot be omitted. Because “特别是” means "especially", but “特别” means "special". It will be a little understanding when there is not "是“。For example, 我喜欢喝茶，特别红茶. It can be interpreted as " I love tea. Special black tea." the listener may be confused: what is "special black tea"?

两句都 加"是" 读起来比较顺 特别跟尤其在这里的意思相同，要用何者看个人的语言习惯。 但在其他情境可能不通用