If you already have the 770, run right over and bring that embroidery module home! I had my Bernina 180 for two years before starting to do embroidery on it. Then I was hooked. You buy designs online and many are free. your 770 should have the ability to convert whatever format you buy to the ART format that this machine uses. It should also have BerninaArtink. it's free and allows you to size, rotate, format, edit any design. I'd not buy the Bernina software until you've worked with Artlink for a while. There are a lot of Software programs that are not as expensive as Bernina's and work well. If you want to "digitize" your own designs, the Bernina is nice. I have no inclination to create my own designs and am happy with buying designs from others. It's a lot of work and takes a lot of skill.
I started learning about how to quilt on my new Babylock Destiny2. It's not as easy as it sounds. Everything has its own learning curve.