1- those headliner panels are called .... trim panels
2- I think Jim Carter has the window parts, check around for the best price, the parts will all be the same quality
3- the 55-59 barn doors are all the same, panel or burb - the correct rubber seals for those are available from Steele Rubber, perfect fit
4- I haven't done it, and wouldn't - try a monoleaf
Bill