Important Site Depth Question

Since no one from Site Depth is available nor do they have a phone number, I wanted to ask the following:

Can I manually replace (upload) any of the thumbnails generated by Site Depth in the member's area with a custom made thumbnail?

Can I manually upload full galleries without having the default gallery behaviors override the photo specifications? Hypothetical example: I have thumbnails, large photos, and poster size photos already fully Photoshop'd. I would like to upload them without having Site Depth rip them. Any new sets afterwards can use the default behavior.

Thanks!