Yes. The description of the class feature serves to ensure that the alchemist can infact make potions since normally, extracts are not considered spells, the alchemist has no caster level, and normally all extracts are self targeted. The feature just tells you that your exteacts are spells for the feat, your caster level is your alchemist level for the feat, and use the spells original target line to determine eligibility for potions.
The alchemist gets the feat Brew Potion that means he can use the feat the way it is written in the book. It is not a class ability that allows the alchemist to create potions, it is the actual feat. This is no different than a 5th level wizard choosing it as a bonus feat.
In addition to the normal uses of the feat the alchemist also gains some extra abilities when using the feat. Normally the feat requires a caster level of 3 and can only make spells into potions. The alchemist can use any formulae he knows instead of using a spell and uses his level as the caster level when making potions. He also ignores the requirement to have a caster level of 3, so can create potions at 1st level. If he multiclasses he can use either a formulae or a spell to create the potion.