Delta printers are fun to watch when they are working, but they are a huge pain to deal with when they aren't. Since no single axial move happens on a single axis, but requires a combination of moves, it's difficult to track down errors and fix them. I bought a delta printer (not that one, though) and it's been a nightmare from day one. Maybe you'll have better luck.

A silicone rubber mold will faithfully reproduce all the lamination lines in your original prints, so if you want smooth surfaces you'll have to fill and sand the models before molding. That's doable for medium-sized sculptures that don't have a lot of detail; it's less effective with jewelry. Most people casting jewelry from printed models use different sorts of machines, either resin printers or ones that print in wax.