Installation troubles and bugs

Hello,
I have several problems with the theme:

1.) My website title is very long, where can I change the size of the displayed webiste title since it destroys the design (I don′t want to change the length of the title itself though, just the letter size)? Is there also a way to block the website title to appear in the header (but not entirely, I still want it to appear on Google so it must stay in the code)

2.) How can I modify the size of the slider menue fields below the slider (the ones where the links are displayed)? What happens if I generate another slider in the code? Will this destroy the design or will the fields automatically adopt in size?

3.) The header menue shows some links, it is preset to indicate kategories of posts. Is there any way to easily change these links to site pages instead? I do work with static sites mostly.
I allready tried to change manually in themes options BUT when I added more than two menue links into the menue bar it did not work out and other links (elements) just disappeared in the frontend.
This did not happen in the footer when I tried.

If there is no easy way, where in the code do I have to modify? Which .php page?

Than you