卧：
Ah, I've been writing 卧 a lot these days in Chinese class, as we had to learn everything about the house, that word being the one for bedroom, 卧室。 For the breakdown of that character, 臣chén means a minister, but you must see it as an eye sideways (the box in the middle is the pupil, the verticle lines in the middle the iris (that is the official way to explain the drawing, but you can also see it as the face, with the square the nose and the veritcle lines the eyes). That of course is what the eye looks like when lying down. 卜(bǔ) is now the meaning of carrot, but it is suspected that it is 人 modified, a person laying down and resting his eyes.
昌:
JohnB already gave a breakdown for 昌, meaning that when someone says the sun is coming, thing look prosperous. Of course the time we most write this is as a radical in 唱, to sing (music of the mouth is prosperous? yes, it is the phonetic part, but why do they pick that one instead of say 长, 等等？)
稚:
禾 hé ('grain') and 隹(zhuī 'bird with short tail')
I haven't a clue what that has to do with immature. Someone else come up with a good one. Both of those things can be immature? (well, the bird part is probably just phonetic, but dang, don't we hate when the birds eat the grain before it is mature for harvest...hey, maybe I got something there...)
蒙:
Did you know 蒙 is a boar豕 wearing a grass艹 hat冃? Hahahaha. Okay, won't making any racist jokes about Mongolians and just leave it at that. (but how did the boar cheat the Mongolian out of the grass hat to cover his head is what I want to know)