First off -- I am not familiar with what an "Ip Protection Service" claims to do for you. I can, however, give you some basic patent information that may help you make a decision on what to do.
" have started working on original scientific research and would like to register my findings/data with an online IP registration service. In about 1 year I might apply for a provisional patent, then after another year probably apply for a full patent."
Do you have an invention yet, or just preliminary data or an idea? Remember, ideas are not protect able. Inventions are, but an invention consists of two steps -- conception, which is the idea, and "reduction to practice," which is the step of getting the invention to a point where it could be "practiced." Usually this means either getting the invention to the point of building a prototype or functional mock-up, or at least being able to describe the invention sufficiently so that someone else could build or practice it. If you haven't come this far, you don't have an invention.
In the "conception" stage of an invention, the only protection you have is trade secret -- that is, keeping the info secret.
"Question 1:
Is my IP protected with an online registration service? The service makes a digital fingerprint of the file I wish to register and attaches that to a personal digital certificate (digital ID) - which is then time stamped with a secure (and certified) time stamp."
What do you mean by IP? Is it an idea, and invention, a creative work, what? What exactly is the IP you are talking about?
"Question 2:
Can I contest an application for a patent if it matches mine and if filled within a year of my online registration?"
Yes, and no. The U.S. has a "first to invent" system for patents. Basically, the first person to "invent" an item receives the patent, even if they are not first to file for a patent (there are a lot of exceptions, but this is the basic rule). If someone else files a patent and you can prove that they were not entitled to a patent because you invented first, then you could ask the USPTO to invalidate their patent. This is almost never successful, so don't count on it -- one of the first questions they will ask you is "if you invented it first, why didn't you file a patent?" The patent system is designed to reward people who file quickly, not those who sit on their inventions.
Even though an invalidation action is almost never successful, there are two other ways to assert your rights. First, you could file your own patent application, and the USPTO may declare an interference, in which case the USPTO would go about collecting evidence to find out who the real first inventor was. The other way is to go ahead and practice the invention, get sued for infringement, and then bring up invalidity of the patent as a defense... I wouldn't recommend that one, though!
Your online registration really means nothing.
"Question 3:
Can I register a priority document with an online registration service."
I don't know what you mean here.
"Question 4:
If I register a 'Priority Document' online - related to my eventual patent application - would this also give me IP protection?"
For a patent, no. For a copyright, probably.
You need to give some more information before we can give a definitive response to your questions.
However, in general, for a patent, the most important thing is the date of invention -- that is, the date where you have "conception" and "reduction to practice." This is the date the the USPTO or the courts will look too when trying to determine who is the "first to invent." Date of conception alone really doesn't mean much.
So, if you have an invention (conception plus reduction to practice), I guess registering the invention with the service could help establish an invention date if necessary. However, if you have the invention at that stage, why wait to file a provisional or nonprovisional? Even if you don't have the invention perfected, the only true protection you will have is with a patent, and if you come up with new material after filing the application, you can always use continuations or divisionals to protect the newer material.
Anyway, if you have more information, let us know. You may want to take some time and talk with an attorney or agent registered with the USPTO to figure out all of your options.