USB-C charger – how does it work?

Hello!

I’m going to the US/Bahamas on Sunday and have started to pack a little as I have a question to keep down the number of chargers in the pack!

My laptop is charged by USB-C 65W similar to this: https://ssl-product-images.www8-hp.com/digmedialib/prodimg/lo…. then I have a tablet in the form of a Galaxy S9 Tab, Sennheiser Momentum 4 headphones, GoPro, power bank which only included a USB-C cable without a plug connector.

Now to my (probably stupid) question but can I use the computer charger for all of the above or is the current in it “stronger” and messing things up? The cord has a 4 x 3 x 10cm black transformer (?) which the other products do not have.
Also the other way around, can I charge the computer with the other cables without damaging anything and/or will it take forever to charge the computer?

Last question; is there a big difference between the plug connectors regarding the time it takes to charge? Has drivers with the white apple connectors and lots of other USB->220v connectors..
If so, are there any adapters that are much better than others that are worth purchasing?

Have a nice weekend and thanks for all the help!
Greetings
Andreas