what are the risks of doing one over the other in your application?
What do the requirements say about being able to perform the individual tasks you have listed?
What are your thoughts of which one is more correct?
Having us do your job for you isn't the best way to advance in your chosen field. You need to work out the why/what/when/hows of your application and the testing you need to perform. Even giving input on your position would be better than just asking for us to answer it for you.
Additionally, what are the standards/expectations of your organization?
Furthermore, you also have to keep in mind how you will deal with defects/issues/bagels that are uncovered as you go through the process of executing your test cases. What are the implications of issues as they relate to test case execution?
Assuming that your Login screen has an ID and a Password object, that makes it around 9 test cases min., plus the boundary and unusable characters bringing test cases up to around 30 total.
And you thought on 2 would suffice?