Okay all those that have toddlers at home - I need some help!

Hubby and I are hoping to adopt a child or children between 15 mo and 4 yrs. If our dreams come true we are going to need some help and I find it hard to ask those that I know who are currently parenting toddlers - scared to get the "well don't you KNOW?" I helped raise my niece (who is now 13 going on 25!) but what we really need help or reminders about are things like: What characters, shows, etc. are toddlers wild about these days? Is it too late to start 'baby signs' with a child who is 18 mos, 2 years or older if they are still preverbal? (The three year old we inquired about has speech delays) What kind of things do I NEED for their "nursery" (aside from clothes, diapers if they are not potty trained...)
Any advice/tips for us? I have been doing some reading on the 'psychology' of adopting toddlers (LOVED Toddler Adoption: The Weaver's Craft - will let you know how it works in reality when we get there), but would welcome any wisdom, experience, etc that others can share.

Carrie