Hello, if you go to Pages and edit the home page, you should be able to change some words :)
1- You can remove fields at Users > Profile fields
2- You can change the type of field and add any options to it at Users > Profile fields
3- Yes you can use visual composer :) But the home page is not created with visual composer so when you activate it the page content will be inside of a text element of visual composer
4- User profile tabs will appear once the user fills some information at Profile > Edit, empty fields do not show
