It might be easier to see community consensus if each proposed rule is posted in its own answer to allow separate voting. This will then be similar to the other Meta questions tagged "default-rules".

Should i split the question to ask for each rule separately?

I was commenting as a hint to answerers. I don't see a problem with several related rules being discussed under one question - that's similar to how the other "default-rules" questions work.

The concepts you have listed in the question are all very closely related, so I like them being in one question. I just meant that if an answer gives a rule for string length and a rule for number of decimal places, then someone may agree with one rule and disagree with the other, and voting cannot express that unless the 2 rules are in separate answers.

Yes. But if we split answers, wouldn't it make sense to also split the question? One question for Integer size, one for list lengths and one for "floating point" accuracy?

Similarly if an answer gives 2 rules for string length, they cannot be separately voted on. For example, if someone says "string inputs only have to be supported up to N characters" but also says "for language X it's M characters" then someone may agree with the general rule but not with the exception for language X.

So I think splitting answers will be needed even if this is split into more questions. I don't personally see a need to split this question, but I don't see a problem with splitting it either.

One thought which makes me lean towards keeping it a single question:

The line between different types is not always clear. Some languages have floating point for non-integer values, other languages have fixed point, or an arbitrary precision decimal or rational type. Since there might be some overlap there may be an advantage to keeping all the discussion in one place.