Daily. Every day you get p/360 percent to the amount in your account.
Yes, in a calendar year of 365 days you will accumulate more than p.

Typo corrected.

Yes, that's what it means. expected what your function returned to deeply equal the expected value.

No, there is no such test, read the error message:

expected [ '1', '2', '3' ] to deeply equal [ 1, 2, 3 ]

You returned [ '1', '2', '3' ] that's not the input value and there is no conversion required anywhere, your code is wrong.