Usage of comma and missing words

Hi all,

I am confused over the punctuation mark in some of the questions.

For example:

1)

Earned allowances can be a positive motivator for young people from six to at least sixteen. Especially when they can buy anything they want with the money.

Instead shouldn't it be:

Earned allowances can be a positive motivator for young people from six to at least sixteen, especially when they can buy anything they want with the money.

Reason: If the comma is missing, it will cause sentence fragment.

2)

I know that some might think that a ten-years old should not have to think of the pressure of the real world, that kids should allowed just to be kids.

Instead shouldn't it be:

I know that some might think that a ten-years old should not have to think of the pressure of the real world and that kids should allowed just to be kids.

Question to ask: Can model verbs like should have an 'ed' at the back?

3)

Too many kids are truning bad today, trying to take the easy way out- they cheat in school, they scrape by at low status jobs they hate and drift off into a clouds of drugs.

Instead shouldn't it be:

Too many kids are truning bad today, trying to take the easy way out- they cheat in school, they scrape by at low status jobs which they hate and drift off into a clouds of drugs.