From page 58 of core:
Alchemy (G): The character can identify common alchemical substances, potions, and poisons with a proficiency throw of 11+. If the character takes this proficiency twice, he can work as an apothecary or alchemical assistant. If the character takes this proficiency three times, he is an alchemist himself, as described under Hiring Specialists.
From hiring specialists, on page 52:
Alchemist (250gp/month): Alchemists are valuable specialists because they dedicate their expertise to creating potions and other concoctions. They may work as assistants to mages to help them create potions. They may also research new potions as if they were 5th level mages, but at twice the base time and cost. See Magic Research in Chapter 7.
So, in order to create potions using alchemy the proficiency would need to be selected three times.
From page 118:
Formulas and Samples
A formula is a magical “recipe” for the creation of an item. A spellcaster automatically has a formula for any magic item he has previously created. Formulas may also be found as treasure (emphasis mine). A sample is simply an existing magic item that is available to the spellcaster while he is working.
The fact that formulas may be found as treasure suggests they are physical things. At this point, I would like to assume it is written text giving directions, so formulae can also be lost or stolen. I am willing to allow PCs to trade potions they have
right now for the formula needed to create the
same type of potion I rolled for.
Also from page 118:
Special Components
Creating magic items requires special components for each spell effect in the item. Components are usually organs or blood from one or more monsters with a total XP value equal to the gp cost of the research. The cost of any special components is in addition to the base cost of the research.[emphasis mine] If a character does not have a formula when he begins creating the item, he will not learn the special components until the work is 50% complete. The Judge will determine the specific components required for each item. Different formulas for the same item may require different components. For instance, one formula for a wand of fireball might require the fangs of 20 hellhounds, while another formula for a wand of fireball might require the ichor of four efreeti.
Sorry guys, but this has just too much potential for adventure for me to pass up. Y'all are going to need special components to create magic items. I am willing to assume, for the purpose of speeding things along, that you will already have had any monster bits needed to pre-create items.