If you have custom/modified WMO, I can't help you, try what dahaga wrote.

If you are using blizzlike WMO:
1) Make sure you don't have 2 WMOs spawned at same coords (duplicated object, made by 2 presses of ctrl+v, import from txt or just bug of saving ADTs).
2) Don't spawn M2s inside of WMOs with indoor spaces (especially buildings and caves). Use only gameobjects and doodad sets for spawning interiors, otherwise follow dahaga's advice.
3) Make sure you have flattened terrain under building and that you have holes on right places. Objects can flicker even when you are running on floor which is too near to the ground texture, so also make sure your building isn't too "deep" in the terrain texture.
4) In cellars and caves make sure that you have terrain texture everywhere enough high above the ceiling.

Water and Ocean have different "waves" on their textures and different sounds, but there difference between them ends.

There is no tool to create water exactly as Blizzzard does. Yes, SDL 1.3 has Auto Opacity funkcion, but its far from the one which is used by Blizzard. Don't expect miracles.

Ah, seems you are not familiar with game_events. Game_events have 2 base funkcions (when refering only to NPCs) - they hide NPCs which are marked to not be spawned during them, and unhide NPCs which are marked to be spawned during them.

For instance, you will create game_event with ID 5 which will occur once per day for 8 hours, meaning it will  be active only, lets say from 8 AM to 4 PM every day (this is done in game_event table). Then, you can add creature into game_event_creature and link it with event.

For instance, you want creature with GUID 654 to NOT be spawned during event (it is lets say blacksmith who is sleeping at home, but during this event he's working at smithy, so you will want to have sleeping blacksmith hidden) and creature with GUI 721 to BE spawned, because thats the blacksmith, who is at smithy, going around, working there and so on.

So all you will need to do is to add 2 rows into game_event_creature, one will have eventEntry 5 and GUID 721 (NPC 721 will BE spawned during event with ID 5), while the second row will have eventEntry -5 and GUID 654 (NPC 654 will NOT be spawned during event with ID 5).

Now, you have 2 blacksmiths, one spawned at forge only during the event, one despawned during the event, meaning whenever there will be no blacksmith at forge, he will be spawned at home. Then you can just create two waypoint paths with scripts, emotes and such stuff, one for man resting at home and one for our heroic worker and... you are done.

Encountered similiar problem with Titan's Grip, while I wasn't able to force NPC carry 2 two-handed weapons at once/two-handed weapon with shield. Learning a spel, adding an aura and so on didn't help at all and I don't know if it actually can be done without some coding in core.

The easiest idea which comes to my mind is creating custom spell, which causes caster to attack for weapon damage with off-hand weapon while playing emote for off-hand attack and placing this spell to event/smartAI with about 2-3s cooldown.

Problem is that server work with most of funkcions related to spawned NPCs and GOBs only when they are loaded, which means that some player is (or recently, a few minutes ago was) on sight distance from them (which can be modified in config, however, it is limited to 533yd, basic is (I think) 150yd). I don't know how many things would need to be changed to achieve what you want, but I fear it would turn your server into happy laggy land.

I would rather think about using of game_events. Just spawn more creatures, give each one of them another waypoint path ofr another daytime and then add every one of them to different game_event. Probably the easiest and the fastest way how to make this work.

Another piece of my level design. Hope you'll like it. Caelarovy kameny (Caelar's stones/Stones of Caelar).:

Just google name of .dll file and MAKE SURE that you are downloading latest version for your OS version. Put it into C:WindowsSystem32 or into Noggit folder. Thats all. You will be most likely forced to download more .dll files, don't be afraid, jsut get them all until Noggit is satisfied .