The role of HR in this issue would be to ensure employees are informed about all relevant policies, ensure all documents relating to employment are completed out, ensure all company mandated training is completed, ensure the employee has physical access to buildings, etc. HR does the general stuff applicable to all employees.
The role of management (including technical leads) is more context-specific around their role. Management would decide on what additional training may need to occur. They would decide what levels of mentoring or tutoring may be required.
HR will often work with management. There is overlap there. HR will struggle without the support of management.
Regarding the sharing of information with employees. My advice is to not go with a discreet system if that can be avoided. If the company uses a Content Management System, you should use that. This is provided that it complies with applicable standards. This means it's in the system the employees use every day. It's way more likely to be shared and seen.
You can't guarantee someone has read something. You can make it more likely by ensuring that information is as terse as possible and relevant.
If information is vital, nothing beats face-to-face. Nothing beats managers buying-into what is said, and discussing it with their direct reports. If you can convince the managers of the importance of an issue, that is how you get a real message to be spread out.
If you are in HR and giving out information to employees on a weekly basis, you're really blunting your ability to communicate important messages.