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On my grammar textbook, there is a part about the possibility to ask a question with just the topic and は, for example:
お仕事は?
That can mean "what is your job?" or "how is work?".
My question is: Are this kind of questions in polite form or in plain form?
As the first answer points out, all of your examples are already polite, but it's because the use of honorific prefixes.
As I originally wrote in that first answer's comments, another situation where は is used as a question is when you ask any question to a person, and then ask the exact same question to another person just calling them by their name:.
【私{わたし}】田中{たなか}さん、スターウォーズが好{す}きですか。
【田中】はい、好{す}きです。
【私】木村{きむら}さんは？
Me: Tanaka, Do you like Star Wars?
Tanaka: Yes, I do.
Me: What about you, Kimura?
In the imaginary conversation above, the polite style is being used, which is shown in the use of the honorific suffixes さん and saying 好きです (as opposed to 好きだ or 好き, which would be plain). However, this has nothing to do with the use of questions ending in は. They can also be used when speaking in the plain form. Imagine I am talking to my close friends 太郎{たろう} and 雄太{ゆうた}:
【私】太郎、スターウォーズ好き？
【太郎】うん。
【私】雄太は？
Me: Tarou, do you like Star Wars?
Tarou: Yup.
Me: And you, Yuta?
In the light of the two conversations above, it is clear that having questions ending in は has little to do with whether the style is polite or plain.
As a general rule, when speaking in informal situations it's more common to skip particles and other words and to be less explicit and less verbose than in formal speech, which might give the wrong impression that questions ending in は should be in plain form. While there is some correspondence between formal contexts and the use of polite form (for example, when talking to your coworkers at the office) and informal context and the use of the plain form (for example, in a conversation between close friends), this doesn't mean that formal contexts necessarily require the use of polite speech and informal contexts necessarily require the use of plain speech. For example, newspaper articles are written in the plain form.
See Does using the characters です at the end of a sentence make almost everything(depending on the sentence) sound polite? and When is it acceptable to use "Newspaper grammar"?.
This is already polite because of the use the prefix お.
This is similar to お[名前]{なまえ}は or お[誕生日]{たんじょうび}は. "What's your name?", "When is your birthday?"
ご[出身]{しゅっしん}は ("where are you from?") is similarly polite but the prefix is different.
I'm not sure what examples your textbook lists. There are some rather standard one's that one could encounter in daily life. I would stick to the examples your textbook lists and not make up new questions; you might not be saying what you think you're saying.
