Though the stowaways may have had individually terrible reasons to try this, I don't think of those five places as being particularly terrible.

Short answer: Yes

Long answer: It depends on the direction. If the hole is in the forward direction the pressure will be higher. If it's on the side or the back then the pressure will be lower. But fluid dynamic is hard so there may be weird exemptions. Anyway the difference can be measured but is small to be relevant in this case.

> say ~ +20° C vs exterior. Could the air pressure be higher?

If you have a sealed container and you increase the temperature ~ +20° C, the pressure will increase, somewhat like 7% (with a lot of guesses and approximations).

But if it's unsealed, when instead of raising the pressure the air will just escape slowly. You can test it with a microwave with a glass of water. When you open it after 1 minute the temperature inside is higher, but it will not hear a pop as a balloon.

The hot air will have the same relative O2 pressure but a lower absolute O2 pressure. I guess this is bad for the survival rate.