While the official Mario Maker has 4 styles, World Engine 4.0.0 typically features styles based on:

Super Mario Maker changed how we play platforming games by letting us build our own custom levels. While the official games are exclusive to Nintendo consoles, fan developers have brought that exact creative freedom to PC.

Version 4.0.0 features native keyboard and controller remapping, improved framerate stability for lower-end PCs, and full-screen HD support. How to Download and Install SMMWE 4.0.0 on PC

You can now attach items to classic enemies, such as giving Fire Flowers to Galumbas or attaching Grinders to Monty Moles.

Yes, the engine itself is safe, provided you download it from verified community channels. It operates as a standalone executable file and does not require you to modify your operating system or install suspicious third-party software.

A: No. The file formats are completely different. However, there are community converters (search “Level 400 converter”) that manually rebuild Wii U levels.