I've been using Prosense theme for around two years and have heavily customized it to get the current look of my website.
I've now found a new theme I'd like to implement (Magazine Basic) and have a few questions on how to proceed.
1) Once I activate the new theme, will I be able to easily revert to the original theme and have the website look exactly the way it did under that theme? (because I expect to have to make lots of style adjustments to the new theme, I'm thinking of putting my site into maintenance mode for just and hour or so at a time as I work on it, deactivating it and reverting to the old one afterwards until the new theme is completely ready to go live. I'd like to minimize downtime in case I run into problems).
2) Do I need to back up my original theme files, or will these be untouched by the new theme customization?
3) Should I deactivate all plugins before changing themes?
Thanks for any advice here.