About voltage and the series/parallel thingy.
Your house is wired in parallel. No matter where you want to plug in a lamp, you'll have the same voltage, so you don't have to figure what voltage bulb to put where, and have to keep several dozen different voltage bulbs (remember this is voltage not wattage). Wiring in series means that the total voltage supplied isn't fed to each device in the series string. Each succeeding device gets a lower voltage than the one ahead of it.
Using a voltage regulator in your model, and wiring in parallel does the same sort of thing. There are disadvantages to using a regulator too. They will usually cost more than a hand full of resistors. It usually means more wire cuz there will be two of them to each bulb/LED. And if you do have 4 or 5 'jillian' LEDs, it's gonna be a much 'larger' regulator (not really in size, but in capacity/cost). The advantage (at least to me) is that it does simplify things. Don't need that hand full of resistors, re-figure the required resistancefor each LED (assuming they're not all the same rating), or forget what the @#$$ you did to start with and have to re-figure the whole @#$ thing again! (I know, I know, write all of it down... but what did I do with the silly paper?)
I don't think there's any advantage to either method, just what you'd rather do.
- 'Doc