There's plausibility to the orange juice theory IMO, using it to make the trip stronger, read
the mushrooms subthread on citrus juice
But no it will not abort a trip and neither will sugar. Though I never know what is more useful, to have it as a placebo effect or to break the santa clause myth and inform the facts.
'How much should I take' threads are not allowed so answers pointed to that question may be edited out.
As to your question how to tell if they are real ones, without being a mycologist it can be hard depending on the similarity of a possible bunk one that is used. There can be inactive mushrooms that look very much the same but also a lot that look totally different. It helps to have some experience with the appearance of psilocybin mushrooms.
Also, the dose is often meant to be for Psilocybe Cubensis, the most common magic mushroom. If nothing else is mentioned I'd assume its those you would get. Other more potent types are significantly smaller.
If you have other things you want to discuss visit
the Big & Dandy Mushrooms Thread, to be found in the Psychedelic Index that we have, I will leave this open a little longer for you to reply.