Antique sterling flatware identification help

[Blazenj1981]

I am researching a number of flatware pieces with monograms on them.

In researching their history I have run into a couple brick walls.

1. How to identify names on the stem of pieces that don't belong to the manufacturer? (??retailer's??). and how can I locate and research these names?

2. how to identify the numbers and letters stamped on pieces and what do they mean? where can I research to properly identify these stamps?

3. How to identify and research monograms, which are on most of the pieces I am researching..and actually how important to historical value these monograms are or could be?..how important to my research and facts about theses pieces do the monograms offer for knowledge of the research?

4. How do I determine exactly what year or time frame likely that the pieces were manufactured if there aren't any marker marks or stamps indicating information for me to research?

Thanks so much for any assists in climbing over these road blocks in my research and knowledge in the world of silver marks and markers marks :)