Hi Hossam,
First of all are using Traditional Web or Reactive? This may have a big impact on the way that you are doing (see more here) although Google Search Engine should work with both.
I'll try to answer your questions below:
1. You should follow the steps on Google Search Console and try to implement the answers to the other questions;
2. You can generate a sitemap.xml using free generators you can find on the internet like Create your Google Sitemap Online - XML Sitemaps Generator (xml-sitemaps.com);
3. You can create a web service that returns you the robots.txt file and implement a SEO rule to make it accessible on domain/robots.txt.
4. You can set tags using the SEO Utils on Steroids forge component. Refer to the documentation tab on how to use it.
Additionally, I recommend you to read this article as it explains how to setup this settings in OutSystems using the SEO Utils on Steroids component.
Regards,
João