1.  yes, not necessarily, and the threat is always there.
2. it's always a possibility, if it happens, you are busted
3. yes, they can.  will they, not likely, but always possible
4.  of course it's possible
5.  well-reviewed providers are less likely to be in cahoots with LE, as it may well be their only source of income.  however, as with all your questions, the possibilities always exist.

You just have to stick with well-reviewed providers who are reviewed by experienced hobbyists.  If you do that, the chances of you having problems with Uncle LEO are greatly reduced.

Good luck,
Swim

Questions
1. I saw few thread about in call out call and potential LE arrest.
If the provider has great reviews that will lessen the threat from LE?
This means the provider is not L E! Other than that the threat remains?
2. If the provider is not an LE, in a hypothetical in call location either in apt or in the hotel (during the provider's tour), if the hobbyists and provider are inside the room what is the possibility that the LE will knock the door! What happened in such a situation?
3. Most of the provider's ads show their face and city name for their touring! LE can follow this and track down?
4. Is it possible that the hotel management can cooperate with LE.
Please don'tBash me for the questions that if you are scared hobbying is not for you like that!
5. If the provider has recent reviews almost every months, if the hobbyists see this provider couple of times before, is it unlikely that she is being used by LE. Any thoughts on that?

The answer will be the same. If you follow the advice here, you lower your risks. But your risk never drops to zero. Any scenario you can think up has at at least a tiny chance of failure. If that level of risk is unacceptable to you, don't hobby.

There's always a slim chance of LE going after providers - and that goes for the famous well-known ones.

If the hobbyist and provider are inside the room, the police cannot go in without a warrant.

And if they do go in,  what proof do they have if they have not witness an exchange of money?  You could just be boyfriend and girlfriend.

More reviews means = less chances of LE.

You worry too much.  Just do it.

than if you see a well reviewed provider. However, there is no 100% not gonna happen, concerning LE.