If the rail is strong enough, you can tie to it but it's probably best to install a dedicated cleat.

I like to drift side on and have setup to do so.  You adjust the angle of the drift by moving the drift sock's line forward or backwards.  The easiest way to do this is by cleating one line from the front to the stern, then tie your sock line to that line.  This way it is easy to move it back and forth and once you find the optimum point, you can then install the cleat.

I actually use a loop to attach the line to the cleat (this makes it faster and easier to  get on and off and is almost fool proof), as I found out in the past some deckies can't tie a line to save their lives and I unfortunately I learnt that the expensive way.

I usually tie the retrieve line to a separate point, I find that this helps with the twist. Hope this helps.

18 Outrage, Johnson 140hp 4stroke and 190 Outrage, 150 Mercury Verado

Tie off to the side of the boat somewhere about half way along the hull if you have a suitable anchor point.  Tieing off from the stern or bow means you are always going to have your fishing lines running along the hull which limits how many people can fish, and means you have to contend with the hull every time you pull a fish up.  I do use a stainless swivel (with a caribiner type clip on it for easy attachment) in front of the sea anchor bridle, and it helps stop twist.  I attach another rope to the tail of the sea anchor (the small end, away from mouth), as the retrieve line.  That way you pull in an empty sea anchor in seconds, instead of spending minutes hauling against the full weight of the sea anchor.  The retrieve rope needs to be longer than the rope attached to the bridle to allow the sea anchor to fill properly, and preferably tied to a point 0.5-1m further along the rail from the  anchor point for the sea anchor to stop twists and tangles.

Cheers,  Peter