I'm so excited to know that you're reading the Bible, thank your for inspiring me to take a closer look at the scriptures. I read them and the still all say the same thing however upon closer examination you'll see that they are 2 accounts being told here, all are correct but one could assume that they all discount one another. The first 2 are relating the same incident almost identically, however Matt. chose to only mention 2 of the women present. Mark tells us that there were 3 (excuse me, I'm fixen to shout about now, GLORY!) Luke confirms that by informing us that Joanna was also present as were others.
Now the scripture in Mark actually reads that she told no man but does say that she told the apostles.
Luke and John are relating the visit after the women had run and told them that's why the angels are inside at this point if you recall Peter out ran them to see for himself. The book of John further details this when he describes the garments already being folded. Now the others have left and Mary the mother of Jesus not Mary Magdalene stayed wondering where Jesus could be then He the risen Lord spoke to her. Then Mary Magdalene came and she saw Jesus and went and shared it with the others.
As for your 2nd question I reserve judgement on the deaths not recorded in the bible because those accounts are not in the bible, which is the only infallible word, the truth for which these and others died for.
In closing 2 Tim. 2:15 says "study to show yourself approved unto God, rightly dividing the Word of truth.
if you're following someone, make sure you know where they're going