OP,
You sound lovely, but that isn't typical behavior, but it can be when children get too much, are accommodated too much, are allowed to be disrespectful brats.
Your children are very young to be so rude.
Clearly life is far too comfortable for them.
My children certainly were never rude like that to me so young, because they would feel consequences bloody quick.
If you want to turn this around you are going to have to buckle up, and stiffen your spine to some serious consequences.
Get rid of all technology and tell them the reasons is they are rude children, and until you see a dramatic improvement in their manners, attitude and behaviour, they will not be returned. And mean it.
Anyone rude about a cooked meal put in front of them should have the meal removed from them and be told to leave the table.
Children in my experience will give you as much shit as you are prepared to accept.
My children were no better nor worse than there friends.
Their friends were all lovely kids because their parents would no more tolerate rudeness and disrespect than I would.
The few bratish children in their classes during primary, all had one thing in common, the were cheeky to their parents and it was accepted.
You need to ask yourself why you are accepting being spoken to by them the way you are?
You are not doing them any favours.
Spoiled children do not make great adults.
They need to learn appreciation for all they have and it's your job as parent to insist they do.
If you don't you are failing them.
As for the walking in the woods etc...lots of children don't like that, so keep it short and when their manners return try and mix it up with things they like to do.
As for now, you need the nuclear option of zero tolerance, to bring a bit of manners and gratitude into your home.
Good luck.