Adverbs position

Hi everyone, this topic has already been discussed. I know I can't ( I shouldn't ) put an adverb between the verb and its object. I also know what "split infinitives" are, and I usually split infinitives ( when I feel the sentence sounds better)

Anyway, in these kinds of sentences:

1. I want to know what her mom wanted to say to my father last week.   Where can I put "in more detail", "at all costs", "better"... I want to apply them to the verb "know."

2. It is more common to say "hola."       I want to insert "just." ..... "to just say hola" is better in my opinion, but some people say "just to say hola".... are they afraid to split infinitives?

3. She said to write it on this piece of paper.     Again "just", and again I'd say "...to just write it..." is better.

4. This software is used to show your IP address.   Here, "just", "not".... but here I'd say "...used just to show...", "..used not to show.." ( I need this structure as an example, of course I could rewrite it as "...used to hide your IP address.")

I just need some advice. I know this is a hard subject, and position of adverbs can vary according to the writer's style, the fact is that learners should avoid bad style since the beginning.

Thank you very much in advance for you help. 

I want better to know, at all costs, and in more detail, what her mom wanted to say to my father last week.

It is more common just to say "hola."  

She said just to write it on this piece of paper. (don't do anything else with it)

She said to write it just on this piece of paper. (not on another paper)

This software is to hide your IP address.