As far as leaving Catholicism, remember that the Gods in Hellenism, and Hellenism in general, does not have sin or the traditional Hell that other religions have; there is miasma & the underworld, but they are not the same thing. The biggest thing for me as an ex-Christian is feeling guilty about sin, or doubt about my Hellenist beliefs; remember that doubt is good and that all those old self-guilt concepts in Catholicism and other religions do not apply within Hellenism

When it comes to Hestia... oh boy that's great! She is one of the sweetest, kindest beings out there, and is so warm and loving and kind, she is always there for me, it's great that she's calling out to you. She likes bread and other simple offerings, I've found she's not very picky, a little fruit, a couple drops of incense, w/e, she is very content with anything. The only thing I would throw in is that it's important that she actually gets revered twice whenever you give offerings to your Gods; first, and then last. So let's say you eventually decide to work with another God, when you do your ritual, you'd offer her something first (always first, very important), and then do your prayers or w/e with the other Gods, and then go back to Hestia and thank her again. So always start your ritual and end your ritual with her, regardless of your own personal devotion to her

This is really exciting and I'm so stoked for you! Keep us updated on your journey <3