If you have template web site such as wordpress, drupal etc. I will check just found vulnerabilities before. Basic package is good for it.
If you have mixed website such as wordpress + unique scripts at subdomains; Standart package is good for beginning.
If you have completely unique website please choose Premium Package for maximum security including subdomains and also your server safety.
Stress testing is included in Premium Package but only if you want it.
I am using both windows and linux for tests. Also using many tools which are made by me or open source.
I have searched the gigs in fiverr related with cyber security and I see my packages are expensive against average costs. However, I offer you experience. You can buy tools for scanning your website but you can't buy experience easily.
Feel free to message me for questions.