Potential verbs are much more common than passive form. However, keep in mind that in speech it is very common to use ら抜き言葉 also.
Some people actually believe that #1 is passive and #2 is potential, while others would say that #1 is both passive and potential (which is the way the standard dialect (東京弁) deems it).
This question may seem strange, but I need to know, as there is an
ichidan ambiguity between Potential and Passive forms, so to make a
more or less proper decision which one form is which.
You should generally be able to distinguish the two from context quite easily. However, you are also missing another possibility. The られる form can also be used as the pollite form, which is neither passive nor potential.
The above should be interpreted as 敬語 and not passive.
However, going back to the passive forｍ again, I believe that one common mistake for Japanese learners is the overuse of the passive form were the active form would be more appropriate. This happens because other languages (such as English) use the passive form more often and in situations were Japanese people would use the active form instead.
ニュースに驚いた <-- Not passive
I was surprised at the news. <-- Passive
These cookies were made by her yesterday.
In the above example, #1 is a closer translation to the English equivalent. However, it should be known that while the English is quite natural sounding, #1 would be awkward in everyday speech and it is most likely that a Japanese person would use a similar sentence like #2.