First Question- To be part of club5050, it means that you have powered up 50% of your earnings in the last one month. You can use tht tool below to check that. https://scribe.steemcryptic.me/club5050

Secondly, Your post should be exclusive to Steemit platform to be considered.

For the last question, The theme science, technology and computing is considered to give birth of so many fields. Talking about engineering, science gave birth to engineering and engineering gave birth to technology. This means that, engineering related topics are still under the science and technology tag.

You are welcome to write engineering related contents using our tag.