Patching..

How painful is moving to another patch? Do we have to remove whole script and upload new one or there is some installation process OR we can do it manually and overwrite what we did not edit??

Thing is, a lot of things on the website are custom now - especially in theme... Will I have to re-do those edittings again?

Updates change core and admin CP's files mostly, and rarely theme's files or pageblocks. And I'm always placing detailed instructions in each update package.

Take a look at the "upgrade" folder inside the proarcadescript.zip file, as you can see, you don't have to remove the entire PAS v1.4 to get it upgraded to 1.5.