REDY said:persecution of jews and christians - why it was that hard persecuted and why it was succesful?,..
Christians were not always subject to particularly strict persecution. Until the middle of the 3rd century persecution of Christians was generally considered a local matter, and they were treated better or worse depending on the whims of the local magnates and populace. As to its success, I'm not sure there is a whole lot of evidence that it was successful. Christianity did grow fairly slowly until the 4th century, but how much of that is due to persecution is unclear; for most people, Christianity just wasn't much on their radar screen.
As to the Jews, they were persecuted about like any other troublemaking group would have been.
pagan religions - how common were eastern religions with Bhaal or Istar, what were kinds?,...
Eastern mystical cults were somewhat known among upper-class Romans at least by the mid 2nd century. I don't know that they attained a whole lot of general popularity outside of their countries of origin, because cult membership tended to be exclusive and expensive, but I can't say for sure. The Severans were fairly interested in eastern cults and promoted some of them (Isis, Serapis, Elagabalus) in Rome.