If I'm reapplying for my I-485 and I-765, where do I file the new applications and do I file them together?

It depends on where you reside and the basis for the application. USCIS provides filing addresses.

You can make changes to your application at the time of the interview.

When do I need to apply for EAD Card?

You can apply at any time, as soon as you are eligible (150 days from the filing date).

Can I take my daughter back to the US without my husband´s permission?

I am afraid this would be a question of custody resolved under the laws of the place where the proceedings will be pending. You have to consult...

Nonimmigrant waiver

To qualify for a waiver one has to have a qualifying relative, a US citizen or permanent resident, spouse or parent.

Can a green card holder re-enter USA after been outside USA for 18 months due to treatment for cancer?what she should do?

I would say that the person would have to apply for a returning resident visa if the person left USA without obtaining a Re-entry permit.

When my fiance can back with Esta.

If you are planning to get married, you need to file I 129F for your fiance.

It depends on the basis for your green card/work permit. Usually, it would take about 3 months.

Will my wife and step daughter's CR1/CR2 applications be processed at the same time?

Both visas, for mother and the child should be processed at the same time unless there are some issues.

When can I file the petition for citizenship? When can i get second GC?

You received a letter.. what was in it? you should consult with an attorney and show all letters you received from USCIS. There might be a second...