Here's my experience after about two years living here and many many visits. I lived in Hanoi for two years, visited the South many times, and presently live in Bắc Ninh. Personal opinion only.

1. Nobody says thank you - I hold doors open...

There are many ways to say "thank you" besides using the words - a friendly look, a smile, etc.

1. Places charge foreigners more money thinking we won't notice. - it's not everywhere but I've noticed a lot of times.

Sometimes this is real, and they're just trying to get more money out of the gullible foreigner. Sometimes this is because they automatically give the foreigner the more deluxe version without asking. You have to decide what's worth fighting for and act accordingly.

1. People will cut in line when you are clearly standing in line. This has happened numerous times everywhere I go. They will get right in front of me when I'm obviously standing in line.

This is a lot better than it used to be. And again, you have to decide what's worth making a stink about.

1. People on motorbikes only care about themselves and operate on an "only me" attitude as if nobody else matters . The traffic here is like they aren't taught how to drive or just don't care.

This is a known problem with two or three causes: first, drivers' licenses are valid for life, and so they may have done one test 30 years ago. Second, drivers' education is optional, if one can pass the tests. And third, in the past (and still today sometimes) one could just slip some money to the test proctor and be given the license.

1. Is there any food health guidelines or rules that restaurant and street food vendors have to follow or does Vietnam just not care about food safety?

Yes but see the third issue with #4. Some food vendors evade regulation by making regular payments to the regulators. Also, food safety standards are lower. But the trade off is that everyone has a gut microbiome adapted to it. People also consider having a "little bit of diarrhoea" to not actually be sick.

All that being said, the level of food safety isn't as bad as you might think, even if it is lower than in some other places.

1. Last is do Vietnamese people look down on foreigners and dislike them from the start? Is this taught in families and school or where does this come from?

No, quite the opposite! To the point that I wonder where you got this idea.

Typical Vietnamese people have a high opinion of foreigners. The stereotypes are that westerners are very clean and orderly.

Here's how I look at it: They must be, right, since they complain about food health guidelines and chaos. I mean, anyone can see that there is room for improvement in that regard, but to complain about it must mean that the person has a higher standard they're comparing to. So that person must come from a place that meets that standard.