Regarding your concerns.

1. Yes, your phone will almost certainly be examined upon entry. There are likely guides online as to how to protect your data so you can safely remove it before entering on YouTube or available via civil rights groups like the ACLU. I’m guessing you’ll need to create a backup, delete everything that might hurt Donald Trump’s feelings before you travel, and then restore it once you’re in the country from the cloud.
2. Probably.
3. Your employer almost certainly has a policy and training for you if you’re traveling internationally with confidential data. I work for a law firm myself and those resources are available for people traveling to other countries. Check with your IT department.
4. This I cannot speak to, but maybe speak to your peers at work who travel internationally or if you know anyone who traveled to the US recently for the World Cup they may be able to provide more guidance.

I’m sorry our border crossings are so stupid.