Number of operations performed in increment operators
Depends. For the purpose of formal analysis, this is usually below our threshold of modelling. Just make a reasonable assumption, or forbid syntactic sugar in your model syntax.

Note that, if you are analysing at this level of detail, working with higher-level languages can be painful. If you want to follow Donald Knuth's lead,


fix a (manageable) machine model and
fix a low-level machine language.


The express your algorithms and this language and analyse. They may not look as nice as high-level pseudocode versions, but analysis is unambiguous.