Hey, welcome back. There's a ton of info and it can get overwhelming quickly, so pace yourself.
Re the maps that went live today, take a week or so and explore what they are showing you. Look at the continents, the kingdoms, the duchies, counties and settlements.
Your Kickstarter pledge will determine much of your eventual involvement in everything.
But for starters, make sure any package you purchased is showing in your inventory. If it isn't, submit a ticket in the technical support forum.
If you know which server you will play on, focus on that map to reduce the noise.
Take a look at the kingdom forums under Servers and join their discords to see if you are able to make a connection. This is a good way to make relationships that could be important down the road.
Depending on your Kickstarter package, you may not need to spend anymore money. Domain and settlement selection (aka the 'land grab') will happen by tier and influence. If you have not locked to a server yet, there's no rush; everyone will eventually get a chance to make their selection. You can also read through the Wiki to catch up on the mechanics and features.
Hopefully those few starting steps are helpful to you!