I am re-designing a website for my boss and her current site designer/webmaster has fell off the planet. Nowhere to be found for the past year!

The site is live online right now and I need to re-design and update. The questions are:

1. Can I re-design and upload the new pages if I have all the information? (FTP addresses, passwords, etc.)

2. With someone else's design on the site, can I just create new pages and upload them without their permission?

3. I have heard a few different ideas for creating the pages (no access to Dreamweaver): Kompozer, Wordpress, etc. Any recommendations?

4. I spoke with a migration specialist and he mentioned something about re-designing the website would mess with google results. Any idea if this is legit?

Thank you guys! I'm a newbie here

1. Yes

2. Yes

3. Wordpress is NOT a design tool.
And you can use any text editor for writing HTML.

4. Changing the URLs will "mess with SE results", if you can redesign without changing page names or paths, disruption will be minimal.

Chrishirst has already asnwered your questions. My suggestion is hire an expert designer/coder if you are new to the design/coding.