Should be a sticky on this; there are loads of threads on here you can search for.
But you really need to demo boats, because everyone is different (size, weight, preferences). Assuming a Remix 69 fits ok; that can take you from noob to pro.
Take a roll class in a swimming pool in the winter; get a solid pool roll, then practice rolling on the river every time out. Earplugs protect your ears from cold water (Docs proplugs are some of the best). You will want a good drytop sooner or later, and other coldwater gear; not sure about the water temps there; here it is icy in the spring when the water really flows. Stick to class II-III until you have a good fast river roll (combat roll), and a solid brace. Swimming class IV or harder is no fun (can be terrifying and dangerous actually), that is why most folks quit the sport.
Here is a good newb thread on a Utah forum:
Sage advice for newbie or inexperienced kayakers