No, you are correct. Once a week is the general time to feed snakes. Feeding them "as much as they can eat" can potentially kill them since snakes have a very strong prey response and rarely encounter unlimited food in the wild. Feeding them this much would be powerfeeding, a bad practice sometimes done by breeders. This will shorten the life span of the snake and often creates disproportionate adults. The man at the pet store was mistaken. Some snakes will stop eating when full but many won't so it isn't healthy.
I do think, though, that the snake is a little small to be a year old. Most of the time they are around 2 feet or so by their first year. You could increase the number of pinkies you feed him or feed him fuzzy mice if he is thick enough. 2-3 pinkies every week should not have any negative effects on him. Make sure that he has proper heating to ensure proper digestion though.
Also... boiled pinkies? Mice should never be boiled. When you buy frozen mice you just let them thaw naturally or thaw them in warm water. But you don't actually cook them... if that's what you're doing. If you were told to do this by the pet store worker they were seriously wrong with the information.
Always feed the snake mice of the same girth as the snake or 25% larger than the girth of the snake. If you need to increase feeding it's better to feed two small mice than one big one as a rule.
For the aggression, the snake really needs to be worked with before it will calm down. Cage aggression (what it sounds like yours has) is very common in snakes. This is caused by feeding the snake in the cage w/o regular handling. The snake becomes used to being fed in the cage and views any intrusion as a threat or as a food source. Either way, it will bite you. Some snakes are more prone to it than others but almost all will calm down with regular handling. The bites of a small snake barely hurt at all and personally I would just handle it bare handed, but if it worries you then you can use gloves. Just don't overuse the gloves or the snake will become used to being handled with gloves.
Some people remove the snake from the cage to feed in order to discourage cage aggression. Since yours seems apt to have this behavior it's probably a good idea to try this. I don't feed my snakes out of their cages because I am used to dealing with them and can read their body language, but if you aren't comfortable with it you might want to try it.
Hopefully that helps.
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