Based on your description of the structure and its features, here are some additional points:

1. The presence of vertical support posts between each pair of rafters suggests that this is indeed a traditional construction method often seen in older homes or simpler structures like garages.

2. Regarding the lack of full-length joists or other supports running parallel to the raftes, it's worth noting that while not strictly necessary for basic structural integrity (especially with such a low ceiling), these elements can still provide additional support and help distribute loads more evenly throughout the structure.

3. The question about whether these posts go all the way down to the floor or are supported by cross-members is important because if they don't reach the foundation, lateral forces like wind could potentially shift them out of place over time, leading to structural issues.

4. Regarding your mention of collar ties and their purpose - you're correct that they help keep rafters from spreading apart due to various loads acting on the roof surface (such as snow or wind). In this case, since there don't seem to be any full-length joists running parallel between each pair of rafter lines, these vertical posts are likely fulfilling a similar function.

5. Finally, regarding your question about whether you can remove existing temporary ties if they were installed by previous owners - it depends on several factors including the age and condition of both the structure itself as well as any subsequent modifications or repairs made since their installation. If done incorrectly without proper support in place elsewhere within framing system (e.g., adding additional structural elements), removal could potentially compromise overall stability further down line...

Rafter ties on hip roof