Customization IPS for themselves

[Guest]

Hi all!

I purchased a license for IPB, but have questions.
Can I install the style, which is not from the marketplace and not take away there license?
Can I add my own settings/hooks and will not take a license?
Pack for $ 25 - the new version of the forum? I chose 3.4.8 and 4 I don't need. That is, I don't have to update it? Thank you! 
Can I install a language pack, which was on nulled forum (I got a lot of changes)?
Can I make changes to the files in the forum? For example to add data to js scripts, codes, etc., or this will invalidate the license?

Thank you!