does anyone fly fish here?? what should i use?

use the same thing you'd use anywhere else on the texas coast, it's not like there is a band of secret fish there eating secret things

I haven't fly fished there but it seems like a reasonable place to find some redfish up shallow. Just stalk the shallows for redfish like you would any other flat. Like Long-Haired Dave said, it doesn't really matter what you use just see what the fish biting and go with it. For starters, go with a clouser. They're pretty dependable

when do the tarpon and spanish mackerel start coming in that way?

generally tarpon/smacks isn't until late summer from what i've heard but you really need to hear from someone down there...

try the texas kayak fisherman forums

You need to be pretty close to or in the gulf to be fishing for those. I suppose you could catch them on the gulf side during the summer. My best bet would be the port A jetties and just look for smacks schooling.