1. No, this resource will return a number of config archives subject to the pagination parameters in the query or the default page size.
2. So first, there's no softwareType response parameter in the GET data/BulkUnsanitizedConfigArchives resource, so you wouldn't be able to filter on that. But second, what this qualification means is that the actual config file content (represented by the files.data query parameter) cannot be used for filtering or sorting. However, all other response parameters can be used, for example files.fileState=RUNNINGCONFIG or diffType=IN_SYNC or .sort=diffType,-deviceId. (And the qualification about sorting is a bit superfluous, since we don't support sorting on nested collections anyway.)
3. So, right now our framework only allows for a binary configuration of whether a resource supports filtering or sorting. Both the Bulk*ConfigArchives services generally support filtering and sorting, so we've marked the values as true, since our framework doesn't support us saying "Partial" or something similar.
I hope that helps