If I switch Jrummy's theme's, from blue to red or whatever....will I have to reinstall all apps and redo all settings etc or will it just be a quick 1.2.3...
I don't think so. Just make sure that the theme is compatible with your current rom. However, to be safe, I would back up your apps and data with Titanium or MyBackUp Pro.
Check the developer of the themes site to see what, if anything, they advise
If you like what I do, thanks
Your can follow me as follows
@dabowerman - Twitter
Derek Bower - G+ - this is where I will be @ the most and where stuff gets released first.
Theming Guides that might come in handy
Theming Guide for Progress Bar
Notification Text Color Change (How to)
Theming Guide for System Text