Several questions from a newbie

Hello Friends!

I know next to nothing about automobiles. The extent of my maintenance skills are replacing spark plugs and engine air filter, and maybe cabin air filter.

The engine is Nissan QG16DE , if it matters.

I hope someone can help me with these:

1. Can anyone pinpoint in the attached pic where the mass air flow sensor is located? And what tools should I use? Any safety precautions?

2. A certain cleaner says on the label, "throttle body and air intake cleaner". Where are these, what tools to use, safety precautions please.

3. As you can see from one of the attached pic, what are those marked with red circles?

4. My instrument cluster works intermittently. They work more often than not. Last time it was failing, I slapped hard on the protective cover, then it was back to normal.
When it's not working, everything does not work (except the digital time).
When it's working, everything is fine (fuel, digital odometer, speedometer, rpm, temperature, digital time).
Any suggestions? If you're going to suggest I check the fuse first, where is it located?

That's it for now.

Thank you very much!

Clusters can be very problematic... I'd recommend giving the folks at https://www.instrumentclusterstore.com/Nissan_instrument_clusters.htm a call. They focus exclusively on clusters and are a great source of information!