> 1. I am not an experienced C++ programmer, so I can't really estimate the price of this.
And getting even less experienced by trying to outsource your homework.
This only ends badly for you in the long run. Even in your best case scenario of staying on the course long enough to get the certificate at the end, that certificate will be useless to you. It might get you a job, but your inability will mean there is no chance of keeping that job.
Worst case, you hand in homework that is so obviously not your own work, and get kicked off the course. They'll just compare the style with your previous efforts.
> 2. I don't know, that's my uni assignment
Well go ask your assignment setter then and find out what is actually wanted.
Vague, incomplete and contradictory requirements are the norm in the real world, get used to it.
Oh, and what have you done about point #1?
"A data structure has to be accepted by a lab tech before implementation".
The first two are easy, should take no more than a couple of hours.
A generic Vigenere solver on the other hand is quite involved.
https://en.wikipedia.org/wiki/Vigen%C3%A8re_cipher#Cryptanalysis