We recently bought a 1918 house that needs a lot of TLC

I am currently looking for info on what the house would have looked for at that time.
These are my questions:
How do I locate original blueprints to determine the original structure?
Where do I look for paint colors that are true to the period?
What kinds of mouldings and doors?
Try calling the County Assessor's office first. They may or may not have blueprints on file along with the original platte of survey. If not, they can give you a heads up as to who in your area stores those types of things. If you are REALLY lucky, it could have been a 'kit' home - YES... there were kit homes as early as the 1840's, so its a shot.
Check any local and state historic societies... They will often have information on color schemes, etc - and MIGHT even have pics of your house from over they years!
Go also, to:
National Trust for Historic Preservation
They have tons of articles, information, sources and suppliers for all you may need. The links will take you to a myriad of information sources which are independent of the site, as well.
BE WARNED!!! If your house is already designated as a historic home, you will be legally required to follow the guidelines of your state's historic society. This should also be a consideration (requiring a LOT of thought) if you intend to get it listed. Check. Sometimes, this information is not listed in the sales agreements and the realtor may not even have known.
It will severely limit what you can and cannot do - even inside the home - so be certain before you do ANYTHING. They even have guidelines for installing electrical and plumbing items. Its a royal pain - and expensive. There are hefty fines (and the cost of removing what they don't like) as well as other penalties. CHECK FIRST.
If you need further help, feel free to email me.... I've done lots of work on historic homes, but my specialty is about half a century older.
Sue