It is not a Reboot. It is a another story. Suicide Squad has had multiple members in the comics. The reason they didn't recast Dead Shot is to allow Will Smith to comeback.
I'm reminded how off Margo Robbie's brooklyn accent is. Her being an Aussie; regular American accent is passible, but not this. Sometimes actors work with voice coaches, but don't have enough time to prep due to short shooting schedules. However, this is her 2nd go-around (third if counting Birds of Prey), She should have it down now. She went for roles like Tanya Harding, certain things can work, think her range is limited. It's a popcorn movie; i know, but little things like this bothers me.
If you get on Gunn's good side you are set for acting work. He really has "his" guys. Michael Rooker would probably be homeless if not for Gunn.
You're right, Rooker's had a weird career...bunch of good roles at the start of his career (Henry, Tombstone, JFK, Mississippi Burning, Sea of Love, Eight Men Out, Cliffhanger) then about a decade of mostly crap until Gunn cast him in Slither (underrated dumb fun movie), and Gunn has cast him in every single movie he's directed or produced since then.
In James Gunn we trust! Also I hope Harley Quinn carry's the whole movie. Did Margot get top billing?
do i need to have watched the first ss movie? haven't even considered watching that mess, but i will if i need it to understand this one.
Don't forget his role as Merle in Walking Dead, which I think played a big role in bumping his popularity again.