Links in WP Admin

I am very new to WP. Have been able to work out most of the kinks except a few pieces here and there.

1. I placed an html in the admin page (custom front page), but the links to image and css folders are not working. I’m assuming that the content is placed in db, which makes sense since the path to the folders don’t work.. However, I’m still working with localhost. What to do?

2. I also need a login for my users to access the post pages. However, after logging in, I don’t want the WP top black bar to show. Is there another way to give my users access to the post pages.

Thanks in advance.