Y14.100 is the starting point of developing company standards. It takes the place of DOD-1000, DOD-100, and MIL-STD-100. It basically points you to the other 14.XXX series documents that you use to develop the specific portions of your company standard. It also has a checklist for tailoring requirements for government work, including appendix for strictly government work.
Start with 14.100. That will get you to what is required on your drawing. Then go to the referenced 14.XXX standards to define the specifics.
I prefer the hardcopy of the standards. It is easier to jot down notes and put bookmarks in the commonly referred to sections.
The DRM from Global Engineering is essentially a combination of the Y14 series standards without direct reference to them. Currently, the DRM is not an industry recognized standard and therefore you cannot say that you follow any specific standard, even though you match ANSI/ASME requirements. To be safe, get the ANSI/AMSE docs so you know specifically what standard you are following when you set up your company standards. Use the DRM for convenient reference.
Check out the FAQ in this and the ASME forum for other standards.
--Scott