I've noticed that constructions with "надо" tend to use a perfective form of a verb. Is there some sort of loose grammar rule dictating this? Or does it just depend on context? For example, can I use either one of the following:
Мне надо помыть четырех кошек.
I need to wash four cats.Мне надо мыть четырех кошек.
I need to wash four cats.
My experience with Russian thus far is that its meanings are often quite precise, so I can't imagine that the two sentences above mean exactly the same thing, but I've seen "надо" paired with both (and the English translations for each), even though I have not yet seen any sort of pattern that distinguishes "надо помыть" from "надо мыть".
After a visit to Wiktionary, I now know that the construct "не надо" is
used in combination with imperfective infinitive verbs.
but that doesn't fully explain all the instances I've seen of "надо" paired with imperfective infinitives. Here's an example:
Безусловно, перед едой надо мыть руки.
Sure. Everyone washes their hands.
Example from Reverso's search results for sentences with "надо мыть" in them.
As always I appreciate any insight you can provide and want to stress that I'd love to see answers that also go beyond the two examples given above and discuss any details that might pertain to "надо" + verb constructions in a more general sense but are still relevant to this question. To start with, what part of speech do Russian linguists/grammarians assign to "надо"?
Thank you in advance.
BTW, I've been to the following discussion threads:
Difference between нужно и надо
Usage patterns of “надо” vs. “нужно”
If they answer the questions I've asked in this post, I didn't see it.