ChildTheme Help.

So, I’m using an AppThemes job board theme, JobRoller, for my site Like an idiot, I have made many modifications to the theme without first creating a child theme. Now, there is a major problem with the site’s geosearch that developed after google maps latest API release. The AppThemes folks have created a fix for the issue in the release of the next version, but of course, I can’t upload the next version without overwriting all of my changes. And no, I don’t know exactly where and what they all are. There aren’t 1000, and probably not even 100, but there are enough.

My questions:

1. Now that I’m in this predicament, is there any quick fix? I.e., can I create a child theme that is styled exactly as my current parent theme is styled (including all of my modifications), and if so, how? Literally, step by step…

2. Once I’ve done this and activated that child theme, I should be able to install the new version of the parent theme without problem, correct?

I can’t seem to get the hang of creating a child theme from scratch, though I’m not entirely sure why – that’s where I need the most help. Actually, I’ve got one created, but when activated, all of the styling appears to have gone bye-bye.