Can anybody direct me to where I find information about whether the game has one single seed, in other words whether area generation within the biomes is a given or differs with every single new game world created?
I do not know how a mod works versus vanilla Minecraft, so I have the following understanding of "seeds", any expert help is appreciated in case of gaps in my knowledge:
1a. Vanilla MC creates a new "seed" every time I create a world. All biomes and the landscaping within the biomes is generated anew and this differs with every single seed and within a biome any landscaping is different, e.g. where you find a lava pool, the top of a hill, etc. However, if you generate a world according to a seed number, you will see EXACTLY the same landscape with every single spawning of that world, no matter on who's PC at what time in which country. The only differences will occur in whatever is spawned in that landscape, i.e. the entities like trees, birds, NPC's, etc.
1b. The NPC spawns, buildings, trees, etc are all generated according to rules and while certain entities/structures (villages, monuments, slimeblocks, etc.) are all generated at fixed places in that seed, the actual NPC spawns are all random, based on given parameters (e.g. when a zombie spawns, this happens according to certain "rules" of spawn, which is a random event, contrary to the fixed structures and entities mentioned.
2. The LotR mod differs from vanilla MC by having a FIXED map with predefined borders, with FIXED regions and within these FIXED biomes (?) and sometimes FIXED structures (such as the Ring of Isengard or the Rammas Echor). NPC's get to spawn randomly according to the same rules as in vanilla, but are region/biome related (e.g. no Orcs spawn in Fangorn, no Evil factions in the Shire, etc.) and at certain structures specific (e.g. even in areas roaming with Orcs, Rangers spawn at camps or buildings only and are thus part of the structure spawn). The biome determines whether a certain type of NPC can spawn at all, how often, etc.
4. What I would like to understand: though the region borders are fixed and possibly the biome borders within these as well (therefore the type of NPC's spawning, the other entities like trees, birds, water, etc. are also fixed, even if at random generated intervals and at random location within the biome) and some firm structures as well, what about the landscaping WITHIN a biome? In other words: when two independent players on independent PC's (so not a shared server) create a new game, will the "ground level" (=the top layer that can be seen when standing on the ground) be identical on the different game worlds (with the exception of the placement of everything other than the ground level, so trees/bushes/boulders/etc. and moving NPC's like animals/NPC'S)? In other words: will the hills, mountains (exception of course fixed structures), lakes, caves, etc., be at exactly the same place, on the same level?
The reason I am asking this is that the way chunks work is that they are VERTICAL and can be replaced by each other. HORIZONTALLY however this leads to landscaping issues, as we can see with some strange builds where the hill gets cut in half to make room for a city or even smaller builds being strangely distorted. If the LotR mod has one single landscape however that is fixed in terms of both VERTICAL (i.e. the given map with different regions and biomes) as well as HORIZONTAL point of view (i.e. that within a region/biome the hills/mountains are rolling in exactly the same way for all players), then copy/pasting chunks from each other's world is a simple feat without any problems occurring in the landscape.