Landmarks

Take a look at the species of wood on the face of the door(not the core, if it is a stave core). If it is walnut or white oak it was likely varnished. This is what vintage millwork catalogs and drawings refer to as "oil-ready". If it is pine and has any knots, it was most likely painted since quality wood has always been available for stain-grade work. A painted door will last longer than a stained (clear-finished) door. Organic materials like wood are prone to photo-degradation without protection. Marine varnish has UV absorbers in it (interior clear finishes like lacquer do not) still light penetrates the finish and affects the wood cells. Landmarks will want to see the adjacent properties, if they have original doors in good repair. Expect to pay 25% more for a stained door than a painted door of the same species.

The short answer is that LPC should not be an issue for you. Even though you are removing paint, you should be covered by engaging in an "ordinary" repair by restoring (not replacing) the doors to original. However, if you want to confirm the procedure, contact LPC's Public Information Officer directly: 212-669-7817. Inspiring fear of working with LPC seems to be a recreational sport for many Brownstoner posters (many of whom have never dealt with LPC). Links you might find useful: LPC contact: http://bit.ly/i7VppA LPC Publications (look under "Rules and Guidelines" to find many publications that can be downloaded at no charge). Especially see the Door section in the publication called "Guidelines and Materials Checklist": http://bit.ly/j3VYo7

Yes, that is something that requires their approval: http://www.nyc.gov/html/lpc/downloads/pdf/pubs/workguide.pdf (scroll down to windows).

I had mine done w/o a permit last year - I think I didn't need one.