I’m also attending YArch this year too, I’m really excited to learn all about the architecture history of Chicago! Attending all the way from Mexico!

I did YArch and found it helpful as someone who took a few studio classes in an unrelated undergrad degree. "Worth it" is a personal choice, whether that month is better used doing something else can only be decided by you but I certainly didn't feel like it was a waste of time. You get a good introduction to Rhino and Illustrator workflows as well as the experience of a design project from start to finish, albeit on a very compressed timeline. There are some aspects of the pedagogy I wasn't a fan of and overall a very formal approach to design, but for some people that can be a good thing. I would definitely recommend the program to people making the switch to architecture grad school from a different field. You will also get a portfolio-ready project out of it which is nice. In my experience the instructors were great and all my classmates were super friendly, you can definitely have a good time too. 3k should be enough for a month in Chicago provided your rent is reasonable.

I personally dont know anyone who uses Rhino professionally or any firms that use that software.

Many firms use Rhino on a daily basis, and many don't. What matters is that once you learn Rhino (or any modeling software) the others become much easier. 

YArch's a solid intro program and UIC is well tapped in to the Chicago- and beyond- architecture scene. I hate to say "network," but if you go to a couple of events and start some friendships during that month you'll learn a lot about what's possible in the field in addition to the course work.

You'll be comfortable in Chicago with $3,000. You should be able to find a sublet for $1,000 or less.