My question has to do with the following phrase/expression: DO YOU THINK IT WISE...to have a piece of cake just before you sit down for lunch?

1) Is it a one-off expression or can this particular format be used with other verbs too?
For example, would it be correct to say: " Do you think it alarming that Jack hasn't called in 3 days?" or "Do yo think it prude to get a safe for my house, in light of the recent break-ins in our neighborhood?

2) If that's the case, then can it be used in the negative too?
For example:" Don't you think it silly to waist time watching TV when you've got so much work to do?"

3) Are there any grammatical etc. mistakes in the whole text above [including this sentence]?

Yes this form can be used with other verbs and your examples are fine except :-

Do you think it PRUDENT (not prude)
To waste time (not waist time)
Great. Thank you for that, much appreciated. Emotion: smile

And of course "prudent" is the correct word...