A:AnswerYou should be able to plug in any external portable drives, just keep in mind that two things:
1. You will need to buy a USB-A to USB-C adapter because the new MacBooks only have 2 USB-C ports.
2. If you plug in a hard drive with either Windows formatting or Apple formatting that is NOT the newer APFS format then you will have to erase any data on them and reformat them.
A:AnswerEvery Mac product I have purchased "open box" from Best Buy came with the full one year. it is something they have been doing with Apple Products specifically. I have an open box iPad mini, MacBook Air 15....and have purchased a watch and iPad Pro....ALL had a one year. You will have your full 1 year apple warranty.
A:AnswerRe: language - Apple indicates you could.
https://support.apple.com/guide/mac-help/write-in-another-language-on-mac-mchlp1406/mac#:~:text=Set%20up%20your%20Mac%20to%20write%20in%20another%20language,-On%20your%20Mac&text=Go%20to%20Text%20Input%20on,Click%20Add.
Re: charger - the 70W is an option you can choose at Apple.com or at Apple store for no extra charge.