I was playing on someone else's server, and there was no one around. I actually have no idea what the timeout is/was. I still find it cheap to have the inventory lost. Anyway. Perhaps this is out of your control, but still pisses me off, and does not encourage me to launch the game to waste my time like this.
Unfortunately it's up to the server admin to decide which despawn time he uses or whether or not players should keep their inventories upon death. We can't enforce any rules... the server files are available for free and basically everyone can host a server. Even if a server admin sets the spawn for new players in hell right above lava (so you constantly die if you join the server or everytime you respawn), that's extremely annoying (and obviously that's a bad server), but ultimately it's the decision of the server owner...
If you want full control, you either have to run your own server, or play singleplayer / LAN / P2P 
I was cooking some meat and there are absolutely NO WAY to tell if the meat is ready, but to look at it until it is cooked. And the time period between "cooked" and "burned" is very small
It's true that the period between "cooked" and "burned" is very small. Originally it was actually intended that cooking meat shouldn't be too easy, since cooked meat restores more hunger and also more health than other foods. It's still not perfect and needs more fine tuning, that's definitely on our to-do-list, but we haven't touched the cooking part in a long time.
And when will it be possible to load their models into the game?
Loading models into the game is already possible through the Plugin API: https://javadoc.rising-world.n…lements/World3DModel.html
However, we will release a few example plugins shortly which allow you to load custom items and models without having to write a plugin for that 
What formats will the model installer support? What restrictions will be? What is the maximum number of polygons? Will it be a separate program? Where can I download it? Will it be possible to prescribe animations to these models? (For example, a door function).
Main format is wavefront .obj, but there is also experimental .fbx and .blend support. When it comes to the textures, we highly recommend to use DDS textures (but jpg/png are also supported).
There is no hard-coded maximum number of polygons, but the more polygons, the bigger the impact on performance. It really depends on what you're planning to do. I'd recommend to keep the polygon count as low as possible. If you want to create a new item or object, I'd recommend to keep the number of triangles (not quads!) under 10k
To create a model, you can use any modeling software you want, e.g. Blender (available for free), Cinema4D, Maya, 3DS Max etc.
Currently you can't load animations unfortunately...
how to add item and custom music ?
If you want to load a custom item, you can check out this class. For custom sounds, check out this one.
However, there will be a few example plugins available very soon (including a custom item loader and a "jukebox" plugin) which allow you to load custom items (and play custom music) without having to write a single line of code 
The example plugins are almost ready.
Does the blueprint preview (before placing the blueprint) contain blocks? Is the "Include Blocks" checkbox ticked when creating the blueprint?
The screenshot you've posted look like a raw text representation of the database... unfortunately you cannot really modify the database that way (changing any values there could break the database). You have to open the database file with a proper SQL editor (e.g. Navicat).
Nevertheless, it's on our to-do list!
