Gawd you can probably shoot 30' of line single haulin' off a spinning rod. 30' is nothing. Just keep the tip of your rod parallel while casting. Plus your tippet is already going to be around 7' so it's not that much. I'd get a #4/#5 or so if it's not too windy, maybe bigger in a freak hurricane. Bigger fish, bigger rod. Two handed rods for Steelhead.
The size of the fly doesn't matter. Casting is all technique. You should get advice from the local fly shop. They've got the scoop on everything.
As for flyes, well, talking flys is a little like talking ski wax. Whole lot of theory and speculation and no concrete way to measure the results.