If your doing a course why not talk about it with your instructor. I would suggest that your course if it involves gas switching will probably be run off tables and that it is important to gain a full understanding of these work before venturing into spending on a computer.
Whilst computers are reasonably reliable (...waiting for Mr Chase to come on about pressure sensor failure
) they are not infallible. You also need to understand why we are switching gas, what happens to the body and about alternatives when something goes wrong. On the course that your doing you will get taught this and the why and reason behind it.
The VR3 is a lovely bit of kit but it may be overkill for what your looking at doing. Better to spend the money on diving and gaining experience.
For runtime schedules a simple Bottom timer will suffice. One with seconds is nice but not essential.
Various people have the Quantum on the board so they will be able to advise. Never used one so cannot comment.
See what you instructors says