Potty Training?

Can some other mamas help me out with the next step of potty training? If potty training doesn’t interest you, don’t bother reading this.

So we’ve started potty training Little Bear, or rather, he’s decided he wants to start potty training. I was going to wait til he turned two, but he just really wants to use the potty. A couple weeks ago he started wanting to sit on the potty before bathtime and consistently would pee. Last week he started asking to sit on the potty more often and would go pee or poop. Today he’s been all about going number one and number two in the potty and hasn’t gone in his diaper once yet (it’s almost noon). I’ve been rewarding him with a butterscotch chip every time he goes which has got him super motivated and he wants to pee at least every hour. Was it a mistake to reward him with treats? How do I phase that out? And what’s the next step? Phase out diapers? And should I buy a little potty? I’ve just been setting him on the big potty but I feel like I need to supervise him every second so he doesn’t fall in. Is it worth it to buy a toddler seat? What are my options?