Flutter: Firebase - How to get a DocumentSnapshot's Stream with StreamBuilder?

There is a particular document in my database I want to listen to with a StreamBuilder. I red, FuturBuilder is for tasks that shall only be executed once (for those people like me which did not know before). That's why I switched to StreamBuilder.

My setup is as follows:

StreamBuilder(
                              stream: FirebaseFirestore.instance
                                  .collection('einstellungen')
                                  .doc('lvgPLifWpRNZrEq3n1Je')
                                  .snapshots(),
                              builder: (
                                context,
                                snapshot
                              ) {
                                if (snapshot.hasData) {
                                  if (snapshot.connectionState ==
                                      ConnectionState.active) {

                                    return Padding(
                                      padding: const EdgeInsets.fromLTRB(
                                          15.0, 5.0, 15.0, 0),
                                      child: Test("Test")
                                    );
                                  }
                                }

                                return Container();
                              })

My issues:

1. If I print myself out the current ConnectionState of the StreamBuilder, I usually only get waiting which I do not understand about why.

2. In case I manage to make it into my if statements (is .active even correct? Shouldnt it be .done?), I am not able to get data from my map called "haushalt". I tried it in kinda endless combinations but everytime I get the standard "nullcheck" message. And even if I try to get along with it using either ! or ?? (last one to set a default value), the message still does not go away.

Some example combinations I used/tried out:

map = snapshot.data!.data()["household"]

map = snapshot.data!["household"]

map = snapshot.data!.data()[0]["household"]

map = snapshot.data!["household"] ?? "Test"

3. Another message I keep getting is about Stream not being a Future. Yeah, right, but StreamBuilder expects a Stream. If I switch back to FutureBuilder I come back to my initial issue where I was only able to paint my widget once.

Looking forward to your replys!

Update

I tried another approach by using where() and get() even though I refuse to use where() just because I was not able to query a single document by its auto generated id...

But even with this approach, I am stuck in the for loop now, because it blames be I am not returning a MapEntry bla bla bla

I am really starting to get frustrated yet again.

I do not GET the difference between when I can/have to use get(), get("field") and a snapshot(). I mean, in this example, I am using get() and the guy I have to code from still wrote snapshot....

This is just so fu...confusing^^

void getEinstellungen() async {
    var collection = FirebaseFirestore.instance.collection("einstellungen");
    var querySnapshot = await collection
        .where("auto_id", isEqualTo: "lvgPLifWpRNZrEq3n1Je")
        .get();

    for (var snapshot in querySnapshot.docs) {
      snapshot.data().map((key, value) {
        print(key);
        print(value);
      });
    }
  }