Vocabulary List and Speech

Matthew signs some words but doesn't say words clearly yet. I've always wondered how many words he understood. A good tip I picked up from watching Discovery: Pathways to Better Speech for Children with Down Syndrome was: Keep a list of words the child understands and work on adding more. For words the child knows, work on getting him to say them.
So I listed the words that Matthew understands as of today. He is 2-1/2 years old. It was a fun exercise and I'm tickled to see the long list (and I think I'm even missing a few words).

all done	down	night night	table
apple	drink	no	teddy bear
applesauce	drum	nose	teeth
around	ears	on	telephone
baby	eat	open	throw
ball	eyes	out	tickle
bath	feed	pants	toes
bed	feet	pear	touch
belly button	fingers	pick up	tree
blankie	fish	play	triangle
blink	fruit	please	tummy/ belly
blocks	give	point	turn
blow	go	pop	twist
blue	Grandma	pour	up
book	Grandpa	pour	waffle
brush	green	push	walk
bubbles	hair	puzzle	wash
button	hands	red	water
bye	hat	roll	wave
car	head	scoop	where
cat	help	scrub	wiggle
cereal	hi	shake	wipe
chair	hop	sheep	yellow
chin	horse	shirt	yogurt
circle	hug	shoulders
clap	hurt	sit
clean	in	sleep
close	juice	slide
cold	jump	socks
color	kick	spoon
count	kiss	square
cow	knees	squeeze
crackers	leg	squish
cup	look	stack
Daddy	milk	stairs
diaper	mirror	stand
dog	Mommy/ Mama	star
door	more	step
doorbell	mouth	stomp
dot	music	stop

I'm not sure if there is a specific list of words kids generally need to learn according to their age or if it matters. I came across some vocabulary checklists on the DownsEd site but they are not free. There are no sample pages so I don't know what the lists include.

We've also had more speech progress recently. Two weeks ago, Matthew started saying "ba" for "ball" while signing it. He's also been trying to say a few words. They may not be exactly how the words sound but he has consistent sounds for each of them.

1. Daddy (da)
2. cat (aa)
3. eat (t)
4. ball (ba)
5. cow (ow)
6. down (da or dow)
7. kiss (iss)
8. jump (da)
9. more (o)
10. all done (a da OR da)
11. milk (k)
12. apple (a)
13. dog (g)
14. bath (ba)
15. shoes (oo)
16. stairs (sss)
17. Grandpa (pa pa)
18. fish (ish)
19. crackers (krk)
20. sheep (baa baa)
21. waffle (ba ba)
22. hop (pa)
23. please (isss)
24. twist (tis)
25. bye (ba)
26. juice (oos)

What inspired Matthew to say "ba" for "ball"?
Not me.
Not his speech therapist.

Would you believe that I owe this speech breakthrough to the 'Curious Buddies: Look and Listen at the Park' DVD?!