Yes. His first career was as an actor. With the money he made acting, or possibly from the publication of his poem Venus and Adonis, he was able to invest in a theatre company, which was the start of his third career, that of a businessman. By owning a share in a theatre company, and later in two theatres, he made better money than he would have done as a mere actor or playwright.
Actually Marlowe was not a rival to Shakespeare. This is because although the two men were born in the same year, Marlowe died in a bar fight in 1593, when he was only twenty-nine. Shakespeare, on the other hand, had only just begun his writing career in 1593 and none of his work had been published at the time of Marlowe's death. Shakespeare revered Marlowe's work, and modeled some of his own writing on his predecessor's. But Marlowe's unsurprisingly small body of work displays much less variety than Shakespeare's did, as Shakespeare had a twenty-five-year writing career in which to expand his talents, whereas all of Marlowe's work was written in a six-year period.
Shakespeare was alive later than when the plague killed Europe.
In searching through a number of sources, I can find no reference to Mary Arden's, Shakespeare's mother, career, other than she was the wife of John Shakespeare. She likely had a full time job raising her family and keeping the house in order.
He started writing plays sometime in the late 1580s. We cannot be more precise than that.
Christopher Marlowe was born in the same year as Shakespeare but his career started earlier. He died just after Shakespeare's career started to take off. Shakespeare at various points acknowledged his admiration for Marlowe's work and inserted homages into his plays. Marlowe used blank verse in a more poetic and powerful way than any previous writer, and Shakespeare used this in his own work. It is not known if they were friends.
There are many debates over William Shakespeare. There are people who theorize that William Shakespeare, was not actually William Shakespeare. These people believe that William Shakespeare was a noble of high birth, who was using the name William Shakespeare to publish writing. There's also the belief that William Shakespeare was actually several different people writing under the name of William Shakespeare. Ultimately, there's no hard evidence to suggest that William Shakespeare was anyone other than William Shakespeare. So the answer is "YES, William Shakespeare was a real writer."
Poet
Scholarly guesswork suggests that Shakespeare might possibly have started writing plays in about 1590, when the Queen was about 57. When she died thirteen years later he was writing more than ever, and kept on writing for ten years after her death.
He was best known as a playwright, but he was also a poet- usually writing poems in the form known as the sonnet. Please note I corrected your spelling of his name.
Yes. In fact, he did some acting while writing his plays. He was as well known or better known for his acting than he was for his writing when he was alive.
Apart from William Shakespeare? The truth is that everyone without exception in Shakespeare's days and 99% of people now know that Shakespeare wrote his plays. The other one percent have weird notions that someone else wrote Shakespeare's plays. In the 19th century it was Francis Bacon. Nowadays it is more likely to be Edward de Vere. It doesn't matter because it is impossible that Bacon or de Vere or anyone other than Shakespeare wrote them.
Good grief, it wasn't a crime to write those plays, was it? In any event the person credited (a much better word than accused) with writing the plays was, during his lifetime and for about two hundred and fifty years afterwards, William Shakespeare and nobody else. The idea that someone other than Shakespeare might have written Shakespeare was not advanced until the mid-nineteenth century by a stark raving looney called Delia Bacon, who claimed Sir Francis Bacon as the author. Other people advanced as possible mysterious authors include Christopher Marlowe and the Earl of Oxford. Since none of these claims require any actual evidence, you can pick anyone who was alive at some point before Shakespeare actually started writing.