Elvish development
The gestation period is one year. An elvish infant or toddler appears similar to a human of the same age, but develops mental and physical skills far sooner. At about age three, elvish physical development begins to lag behind the human norm. While physical and intellectual maturity is attained at age fifty, emotional maturity can be postponed indefinitely.
Time in the Undying Lands
A year of the Trees is roughly ten years of the sun. What change and decay exists in the Undying Lands (the lifespan of animals, for example) is likewise slowed down. This compensates for the slower time-sense of elves; the passing of a decade feels like the passing of a year does to us.
I do not believe that the growth rate of young elves was included in this; it wouldn't allow enough time.
Incidentally, the tenfold slowdown would give you a month in three days like the Fellowship experienced in Lothlorien.
Episode 1: Mothername
Galadriel is between a year and a year and a half old.
The setting is Finwë's house. I decided that Fingolfin, Finarfin, and their families spend a great deal of time there. Fingolfin's portion of the house is technically a separate residence with it's own entrance and Finarfin maintains a house in Alqualondë as well as his upstairs apartments in Tirion.
Amrod and Amras aren't born yet.
Typically, a couple will have their children early in the marriage, waiting until each is grown before having the next. Childbirth takes more energy from an elven mother than a human; families with more than four children are rare. Thus, children are highly valued; the attitude Nerdanel attributes to Fëanor is in bad taste, to say the least.
Of course, we only have Nerdanel's side of the story. Fëanor is probably griping about her and it's probably at least partially justified.
I had to include an early example of Aredhel's chronic wanderlust.
I imagine Orodreth as having his nose permanently glued to a book. He'd rather be reading than worrying about how to deal with people. I don't see him as a 'dullard', whatever Curufin might think.
Episode 2: Galadriel's Tree
Gemstone lore courtesy of Lufia 1: Fortress of Doom (SNES RPG by Taito)
Episode 4: Celegorm's Horse
FYI: Finrod and Amarië weren't doing anything that you can't do on a sofa in a college dorm lounge.
The 'mispronunciations' Maedhros mentions refers to the Shibboleth of Fëanor. He opposed and politicized the th>s sound change associated with the tengwa thúle/súle (wind). Unlike her parents and brothers, Galadriel used the newer pronunciation.