I got the same model fairly recently. I just wanted an inexpensive way to get started. I don't have answers to most of your questions. I have downloaded free designs from the internet, and they are easy to load to the machine without specialized software. I assume you got a book with directions. They are pretty clear IMHO. If you have specific questions about downloading, send me a PM. I don't necessarily plan to use my machine for quilt blocks, just to do some embroidery for towels, potholders, etc. I've made a few appliques, too. Some will go on a quilt, and I made one for a dress I made for DGD. I think the appliques are really fun to do.
I'd particularly like to know how to make quilt labels without going to the expense of software. I'm not sure the fonts that came with the machine are adequate.
I know you can get to a screen that seems to have percentages, so you might be able to increase the size of some smaller designs, but of course, not larger than 4x4 on this machine. That seems to be the limiting factor. I've gotten some really cute free designs as well as paid a small price for some others. Today, I'm working on freestanding lace. The stabilizer seems expensive though. I was able to get some at 40% off, but still pretty pricey for just experimenting with. There's also a bit of an investment in thread. Got some Christmas colors of threads today at JoAnns marked 50% off.
Have fun and keep us informed of your progress and discoveries.