Delta main cabin

What are the perks? Do you get a free carry on and select your seats for free? Nothing really matters besides the carry on and seats because I don't want to pay extra if I don't have to. First checked bag is like $30 each way and ima not pay that much. Plus if you have a checked bag then it's a good idea to get insurance incase it gets lost and I'm not about to pay another 20 odd dollars either (cheap stake here lol)

I'm planning a trip two-ish months from now to go see my boyfriend for the first time in 8 months. Also does anyone know how I can get the best bang for my buck? Like what websites to use, best days to book a flight, etc etc. Any tips or tricks would be most appreciated. I'm used to flying Frontier airlines, but they stopped flying to the town nearest to my boyfriend so I chose Delta