Hello,
I've spent a ton of time on my database relative to how long I've been part of the community. (I'm part of it, right?) But, your second question is easier for me to answer.
I haven't used the in-game #spawn enough to understand it's intricacies. If I want a duplicate of and existing mob, I will use #dbspawn <npc_types.id> then I think #npcspawn create to give it a spawngroupid. I haven't used it much so you may want to check the wiki pages on this
http://wiki.eqemulator.org/p?How_to_..._NPCs&frm=Main
I use HeidiSQL to make the vast majority changes to my DB.
Your first question is difficult to answer because I am not aware of anything in the table `npc_types` that distinguishes a raid boss from a non-raid boss. If I were doing something like what you want to do and I wanted to be accurate, unfortunately, I would probably have to go on memory and other sources and hand pick these.
To make hand picking easier, I would write some queries to make searching for these mobs a lot easier. As far as I know, doing it either way will still take some time to sift through the npcs you want to include as a raid boss. Now, if someone had a list, injecting this list into a table and checking npc_types against this table would be "simple".
The answer to your question will be determined by how much time you want to spend on this minus a list someone already has formulated.