According to Variety's article, Spiderman Returns to Marvel; New Movie Coming in 2017:
Who has creative control, distribution rights?
Sony will continue to distribute, finance, own and have final creative control of the Spider-Man pics.
How can each party use the character?
They’ll work with Marvel, owned by Disney, on how to weave Spider-Man’s character into Marvel’s upcoming superhero films, which includes the popular franchise “The Avengers.”
As Variety previously reported, Marvel plans on bringing the Civil War storyline from the comic books to launch the next phase of films. It’s very likely that Spider-Man will make his first appearance in Captain America: Civil War next year.
What is currently known about the future of The Amazing Spiderman franchise?
According to the announcement, Sony and Marvel will cast a new Spider-Man after Andrew Garfield starred in the last two films, The Amazing Spider-Man and The Amazing Spider-Man 2. Tobey Maguire played Peter Parker in the previous three installments for Sony.