i think there were about 3 busses a day at least going that way, per company, and there are quite a few companies. I dont know for sure how much it costs bcuz i had that stop in Trujillo, so i had two seperate bus trips. peru is a pretty cheap country, it wont be overly expensive. everybody recommends Cruz del Sur bus company, i never did take that one but it has the reputation of being the most comfy and it actually serves food....bus food, but food. but its also the most expensive. the bus ride all the way to Mancora is pretty long though, its probably worth it to take a nicer bus with a Cama seat if you can afford it, i always roughed it with the Semi-Cama to save money and those rides can make you wanna kill people, unless you have some Valium or something, ooooohhh i recommend the valium. ANYWAY.... the thing that kinda sucks about Lima is there isnt a central bus terminal, they're all seperate buildings but they ARE in the same place so you can check around. or you can do it through one of the many agencies but you'll pay a little extra for their service. its not very much more though, and waaaay more convenient.
for food in Mancora, since i stayed at Loki i usually ate the dinners they offered at night at the hostel, they're pretty cheap and they're good. one thing that sucked about Loki is there is no kitchen, so i couldnt save some money by cooking which i usually would do. but, restaurants in Mancora are cheap and good, there is good seafood everywhere, especially on the beach. "going into town" is a funny thing to say about Mancora.. i mean this place is a one-main-road kinda place, really tiny. but there are the typical stands and bodegas and people going up and down the beach with food to sell along with the tons of restaurants lining the beach and main strip. and people at your hostel can recommend things to you too.
i wish i had pictures of the crazy boats!! thats one other thing i wanted to tell you actually, i dont have pictures because i NEVER took my camera to the beach, or anything else of value. every day, i mean eeeevery day, you hear about someone's camera being robbed on the beach or whatever. usually they were not being real smart, like walking down the beach alone at night with too much cash and valuables, you just dont do that there. during the day if you want to take your camera to the beach and then right back to your hostel, i'm sure thats fine, i just didnt want to risk it. when you go to the beach at night for parties or whatever, take only what you need. i dont want to make the people in that sweet town sound like a bunch of thieves, its not like that, but of course a few ruin it for everyone. i loved the people there, i dont want to give the wrong impression. dont be scared, just be careful.