|Nicey replies: Yes very prudent of you to touch base with us.
Ideally you should have either 2 sugars or none. Our ISP Mr Borrill has the most annoying amount of sugar in the entire world, a third of a teaspoon, for which he has a special teeny-weany teaspoon at home. He says he can drink it without now, but really it's plain that he would still prefer a tiny little bit of sugar in it. If you are going to be awkward and have sugar at least make it worth while.
As for biscuits this is a good opportunity to do some team building. As engineers you can discuss the dunking merits of one biscuit over another through which you'll learn to respect and value the input and opinions of the other team members. You'll also quickly spot the clueless ones and assign them tasks accordingly. Given that there are 12 of you, you'll need to choose wisely avoiding things that come in packs of ten unless you want to buy 6 packs and everybody have 5 of them.
Mind you given that you are students you may be over-reaching yourselves financially to go beyond entry level biscuits. As a student I ate lots of Ginger Nuts, Digestives, Malted Milks and Fruit Shortcakes all excellent Dunkers and whilst I never built a racing car I did manage to loose all of my third year Molecular Biology project results which led to me being advised to try a career in computing instead.