In short yes to your first question. But very few timber shops do engineering in house. At the same time, it's not really a big deal to outsource the engineering. I would highly recommend going with a specialty timber frame engineer. You can find who is licensed in your state here:
https://www.tfguild.org/find-an-engineer. The engineer should be taking a more holistic look at the whole building, and more than just the load at the ridge. The process will likely take longer than a stick truss company.
And yes, trusses can either be shipped assembled or disassembled. Factors might include the span, the height, site conditions, weight, etc.
