You just have so many questions that a response would take forever. Also read the self help center as there is tons of good info on there for newbies.

That will answer at least 80-90% of your questions.

Get back to us after that and ask the questions you are still unsure about

I'm not a P411 member myself, but generally that organization gets lots of good props on here.

Yes on the dummy phone

More reviews is better than too few.  If you don't like the high volume gals, then avoid any that have more than 4-5 review/month.

You must give info to agencies and screening sites, or they can't be sure we are all safe.

Stick to the well reviewed gals to avoid the drama and pimps.

Most legit providers are around $250/hr. and up.  Some rural areas are lower, and large urban areas tend to start around $300.

Not all high price gals are better than their counterparts, but generally there is a correlation.  Become a VIP member and read the reviews to know what the market is.

Not sure about agencies that screen, but any gal worth her salt gets tested regularly.

Like I said, the Newbie Manual will give you lots more dos and don'ts.

Read up and if you still have questions, please come back to us.

When you say they got busted because they were on p411, please be specific, do you mean they got busted by LE or by an angry wife/girlfriend?  It would also help if you could link to the posts you're talking about, I'm just a little paranoid because applied for verification pretty recently.

For what it is worth my 2 cents:

If you can find a way to have a spare phone then get a throw away phone.  If not then use your phone with googlevoice but only if you are tech savvy enough to configure google voice well enough not to merge your worlds.  When you are not hobbying uninstall voice form your phone, then reinstall when you need to make contact. you can 'text message' from your googlevoice account from a computer.

for all computer work use an anonymizer. TOR works well for example.

# of reviews - no hard rules.  The odds of a provider being reviewed and flipped and you getting busted from that are very slim. if there are relatively recent reviews then likely fine. If in doubt PM the reviewers.

No such thing as too many reviews in my opinion - just means lady been around awhile.  If you were hiring an attorney, contractor, or doctor you would want someone with the most experience.  A lady with a ton of reviews will know what she is doing and you are getting a sure bet in terms of performance, in my opinion.  If a high number of reviews makes you nervous due to how many other guys were there - get over it.

I don't give out personal info anymore.  Join P411. Myself I see UTR gals and AMP gals - two opposite ends of spectrum.

Highly unlikely an agency dumps your info.  They likely keep secure, but they keep it.  

To avoid scams stick to reviewed girls.  You can't avoid "pimps" for the most part but you don't have to deal with them.  most girls have a 'booker' and folks running an agency are pimps in the strict definition.  You want to avoid hostile/predatory pimps and sticking to well-reviewed and reputable agencies should help with that.
no set entry fee but in general outcalls range between 250 and 450 based on city. incalls vary slightly less.

more money does not mean better quality once you are above the threshold but it may mean more services. quality is in eye of the  beholder.

don't trust anyone else about STDS.  protect yourself and stay in your comfort zone.  never take anyone's word about how much they test or how clean they are