Oddly enough I fished one of those out of my bag last week, its been in there for years, way to thick line, 50 lbish, beads all over the place, booms and swivels. I actually suspended it all under a sea float because I was not in a good mood (another long story). However, normally best to make your own trace up to suit. Link swivels are useful on the end of your line as they enable to change your weight quickly, the same on the end of the trace to change that quickly if required.
There's an argument about swivels, do they work and stop line twist, I don't think they do much but link swivels are useful.
I have been all through the gamut of sea traces and like you said, a weight on the end, a loop in the line 12/24 inches above the weight and a hook trace attached to the loop about 3ft is all I do these days if beach casting. The less the better, more hooks just slow the cast down as do more beads , swivels etc.
Some think beads of different colours attract fish, I forgot to mention the shop bought trace also had sequins on it, well, I dont know but I doubt it, more to catch the anglers pocket is my guess.
However a couple of shop things are useful just to keep in the bottom of the bag, one day you might find a use for one.
If you are thinking of float fishing in the sea I have just posted a bit about that on the " how did you get on" thread under general fishing, you might find it helpful. But you work out want you want to do, its as much as what your happy with as anything else despite others advice and preferences.
As to knot for hooks, I use the half tucked blood knot, I dont have a problem with that, leave a tab of line jutting out when you cut the excess line off, about 1/4 inch, useful for holding a lugworm up the line if you use them as bait-some prefer the shank tied ones but I find the other easier to tie.
