Operas tend to be expensive so plan accordingly. If you find the only seats you can afford are in a high balcony or well back in the orchestra section, take a pair of opera glasses or small binoculars. As for the sound, most concert halls today are well designed and no matter where you sit you’ll hear everything. By the way, one thing you will notice is that none of the performers wears a microphone. Their voices are so powerful they don’t need them.
There is always a full sized orchestra on hand and they sit in a pit just under the stage. If you’re high enough up in the balcony you’ll be able to get a glimpse of them but that’s about it. After all they aren’t there to be seen, just heard. However, they will probably be formally attired. Opera does have its traditions. The conductor however, is quite visible. He will approach under the glare of a spotlight. His podium places him above the orchestra and just below the level of the stage so the performers can see him. Notice your author uses “him” to describe orchestral conductors. In this arena it is still very much a man’s world.
As a first time opera-goer you’ll probably welcome the intermission. Just pretend you’re at a football game and it’s half time. Go outside and have some refreshments, and listen to some of the comments others make about the performance. It will be an education.