1: there was no new release for a long time, partially because a major code rewriting of Maratis Core and Editor is going on.
You can follow the development here : https://github.com/anael-seghezzi/Maratis-4

2: Yes, there is a "publish" button that compact your game files and embed it with a player executable.

3: Maratis Editor is the toolset that allow you to level design and test your game in realtime. Maratis Engine is the 3d engine itself (it's possible to make a game without using the editor) and when publishing, the player only uses the engine. Maratis SDK is only an interface to Maratis Engine (in c++).

4: Yes and No. There is no terrain engine, but you can export a terrain mesh from a 3d software. It means you'll have to optimize the visibility yourself if you want to handle large terrain. Or to extend a custom plugin in c++ to draw terrain the way you want. Water and Ocean can be created with GLSL shaders, but again not by default.

5: Lua is used for game logic programming. C++ is used to create custom plugin, mainly to do things that need fast computing (custom pipeline, rendering, complex AI...).

You need programming to make a game, but depending of the game it's more or less difficult.
Lua is a very simple language to learn. C++ is much more complex (easy to learn but years to masters).
I suggest to start simple and up the complexity step by step, while following a solid structure.

Bests

1) Does have Maratis new releases? when, how often?
2) Can I make an executable?
3) What's the difference between Editor and SDK?
4) Does Maratis support Terrain, water, ocean or large terrain sets?
5) Do I need to learn a programming language? I read that LUA is used as a interface.

I'm trying to accomplish a project by mixing the graphics and playability of homeworld 2 and the scenarios and history of Fleet Command. Not a programmer but I have 3d knowledge and modeling and texturing (3d Studio Max, Blender). I was thinking of start using unity but the lack of Linux Editor drove me to find alternatives free and open source and the flexibility of porting. 

Anyway, I'd just discovered you and wanted some clarifications and expertise.

Thanks & Regards.