Hi there, for your first question I found a thread that might be helpful to you:
https://community.qualtrics.com/XMcommunity/discussion/4840/css-for-the-languages-translations-selection-box
In that, jainshubham provides some code that can be pasted into the CSS of your survey to provide the spacing. Below for reference/;
.LanguageSelectorContainer {
padding-bottom: 70px;
}

For your second question, while I am not sure how to actually decrease the font size, I found another thread that touches on altering the text that gets displayed.
https://community.qualtrics.com/XMcommunity/discussion/4401/edit-language-selector
In that, PraDeepKotian_Ugam provides some code that can be pasted in the Header of the survey's Look & Feel. Changing "English - United Kingdom" to just "English" is the example they use, though I think the selection box will remain the same size. Below for reference:


Alternatively, you might show the language selection on just 1 or 2 screens. Below is a thread that covers how to do that:
https://community.qualtrics.com/XMcommunity/discussion/554/getting-rid-of-language-changing-option-in-survey
In that, TomG provides somecode to be pasted into the CSS of your survey to hide the language selector throughout.
.LanguageSelectorContainer {display:none}
Then, on individual questions, you can include the below Javascript to have the selector display
jQuery(".LanguageSelectorContainer").show();