1) Yes, they should all come back regardless if there are values or not.
2) There is no such account we can provide you access with but I would argue (pose the question to your customer) that you do not need to get the formats for all activity types as a lot of the activity types are not really of use and can result in large volume of unnecessary bandwidth/data (i.e. change data value).
I would request from your customer the specific Activity Types that they are interested in and just focus on those. Typically, the types that are "interesting" and of use are the ones listed in the link you referenced above.
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