My guy went off his at 13 months, cold turkey. He asked for it and I told him I didn't know where it was (I really didn't) and he was a little sad but didn't cry. It took him a little longer to fall asleep that night, tossing and turning, but he didn't ask for it in the morning and until his nap (I still didn't know where it was.) He didn't ask for it that night and went to sleep just fine. I found it the next morning but tossed it as the worst was over, and after the third night when he asked for it but didn't fuss, he never asked for it again. I've read and heard that the first 3 days are the worst, and that's how it worked out. My cousin's daughter has a large space in the front of her teeth and misalignments, and is speech-delayed because of staying on a paci too long, her ped and the dentist told mom in no uncertain terms that she did the damage to her daughter's teeth and development, so I was really happy his weaning went so easily.
Since you really want to break the pacifier use, i would suggest you have a replacement item like a stuffed animal or blanket for him to soothe himself with, and introduce it when you take the paci away and use it as a substitute. The longer they are on them the harder it is to get them off them, so unless you want to go cold turkey, if he's using the paci all day I would hide it except for naps and bedtime. Then in a few days move to him having it just at bedtime, then in a few more days don't give it to him at all. Focus on his new stuffed animal, read him books, fill his bedtime routine with a bath, a massage with bedtime lotion, and relaxing, calming music, so he thoroughly relaxes and falls asleep without missing it. If he does miss it and cry for it, as hard as it may be for you, don't buy new ones for him.
As far as him replacing the paci with his fingers, children do this to soothe themselves, sometimes because they are stressed, so don't tell him he has to stop doing it, which could stress him. My dad would tell my brother to stop and he would hide and do it, but my mom wouldn't say anything but would keep my his hands busy whenever she saw his fingers going towards his mouth. Redirect your son when he show signs that he's about to suck his fingers with a special toy or activity like coloring with crayons, finge rpainting, blocks or puzzles he needs both hands to play with, holding and reading a book, giving him a snack to eat, etc., to help draw his attention away from sucking his fingers.
Of course he may still suck them at nap or bedtime when he's not busy, but children usually stop sucking their fingers and thumbs by 4 or 5 so hopefully in time as he gets more involved in other activities and interests he'll stop entirely.