css alteration

Hi! Can anybody help me with css. i have very little knowledge on it.

I just bought a theme (paradise) from themeforest n now i wanna make quick changes to some part. my website is

1. i set my posts to full-width page however it is still showing as a 2-column page layout (without the sidebar widget of cuz). how do i set to a 1-column post?

2. the theme allows me to pick selected colors (e.g. blue, black,etc). how do i add more colors (e.g. brown)?

3. how do i remove the date, author, category and comment box for every post? i mean like literally not showing on my post?

4. the theme only allows one navigation menu. how to add another navigation menu?

every help is apprreciated. tks in advance.