Hi there Behrad,
I have 8 years experience in wordpress, drupal and on also joomla (on the old times) and some custom php frameworks. Since 4 years ago I am only making websites with wordpress + custom code (plugin developement) . Anyway, I respect your opinion about wordpress and security but isn’t accurated and want to give you some examples.
Actual Websites running wordpress:
About security Wordpress is It is highly updated, as a open-source is the most active on that field. But remember, security is more than choose a CMS. Is a lot of things like the hosting you choose, the configuration they use to protect folders, and the hardening on the whole project.
First of all. I don’t want to sell my services, please take it as a recommendation
1-You must have your ideal cristal clear. make some draws with a flowchart, just a data flow diagram to express how the website needs to run like:
You can use free https://www.draw.io/ to make a simple draw and works nice
2.Again, your worker must understand fully your needs. Put milestones like:
1-have a registration process
2-Make the form to add new entries from users
3-Make a search box
3.Put a realistic timeframe for all. Your proyects seems big, so will need at least 1 person with full experience working on that or a team that can handle this amount of job
4.Before start the project you will need an estimated budget and description of the work. Isn’t the same to get some nulled script without license and make your website than make all from scratch the right way. The results are important but also what is under the hood to avoid future problems…
Of course on fiverr , upwork and other plataforms (I worked on most of them) there is amazing people, people with really good skills but just be sure to do that steps to don’t lose time and money