Re: Knot to swim bait and iron
For iron, I'm tying mono or flouro directly to the welded ring with a Trilene/improved Trilene knot, but mostly because that muscle memory goes back 35 years. Uni is a solid choice, as is San Diego Jam and countless others. Ditto for swimbaits that I'm trolling.
For swimbaits I'm casting, I use a non-slip loop. I'll use this for live/dead bait hooks without rings, too. For ringed hooks, palomar for light line, knots listed above for heavier line.
The only extra snaps or swivels that I usually use are on trolling rigs to snap to rigged clone or cedar plug leaders.