Beautiful birds you have!! I have always loved these guys, all of the Bourke's, Linnies, etc. are just wonderful birds!
You said that you've always had "larger parrots" and aren't familiar with the smaller parakeets...Well that actually makes it easy in-terms of their wants and needs, as they are basically the same! Parakeets are every bit the parrot as an Amazon, and African Grey, etc. They are very intelligent and need to be stimulated just as much so that they don't get bored...LOTS AND LOTS OF TOYS!!!! And as mentioned some foraging activities and things to chew on, such as a Kabob...
The nice thing is that these guys can't go through wooden toys in a day like larger parrots can, so if you buy a bunch of different toys for them, they will last a long time. Make sure they have plenty of different types of toys, as they actually not only like wooden toys, rope toys, etc., but they also love the cheaper, plastic toys as well.
The grit thing is hilarious, as up until the late 90's-early 00's, everyone who had a Budgie bought boxes of grit and typically just poured some on the bottom of their cage, on top of the newspaper or cage liner. And from what I've heard, they actually will eat the grit, even though they don't need it to properly digest their food...Somewhere along the way it was made clear to the public in-general that Parakeets (all sub-species) do not need grit to digest their food, and people stopped buying it, although I STILL SEE BOXES OF GRIT SOLD IN EVERY GROCERY STORE, WALMART, ETC.! As little bird/parrot merchandise that your typical "Grocery Stores" sell, they all seem to carry those damn boxes of Grit!
And thankfully they do still all sell those cheap boxes of Grit, as I just recently brought home a Ringneck Dove, who DOES NEED GRIT!!! LOL, 3 weeks ago when I brought him home was the first time I've ever bought one of those little boxes of grit! I keep a little bowl of it on the floor of his cage next to his food (he eats from the type of feeder that chickens/ducks eat out of), and he does his thing...