Short Answer: Ehhhh Sorta
Long Answer: We will first begin with spawn dummies. As you said, adding a dummy to a map is how you add things like spawns, so you are correct, just remember to always start at '_101'. This goes from everything from solo, team, and NPC spawns. Naming conventions are as followed, spawn_(*solo_*, *team1_*, *team2_*, *npc_melee_*, *npc_range_*, etc)_***. As for worlditems (AP/ HP/ AMMO/ CTF Flags) the positions can be grabbed using a dummy, but they are not needed in '*mapname*.RS.xml'. All worlditems are spawned according to spawn.xml in the 'Matchserver -> Map -> *mapname*' folder. They will not appear unless they are placed in this file. If the spawn.xml is created if you make a name sucbh as 'spawn_item_team_bullet02_01' is beyond me but then again, I have not yet tried.