No grip needed at all. There are plain leads available of course. I prefer large olivettes. Less obtrusive all round and cast clean and straight. Inline best option for this.
Make sure you twitch that bait. If you are trying worms ask for americanos, rather than coreanos. They're like our white ragworm and boost the chance of dourade about tenfold. And definitely get some fine baiting needles. Those fish can nearly untie knots with their lips. Fantastic challenge,good fighting and as I'm sure you will be aware, superb eating.
I anticipate you'll be able to translate the Spanish to what I guess will be the requisite french. Dourade Royal is I believe our gilthead.