(1)
Unactivated Windows 10
Unactivated Windows 10 works as per normal and can update, except it will have a watermark and cannot customize themes. If you have a previous Windows license, you can upgrade it. However clean install using the CD-key may not work.
You can buy from other sources that are cheaper or free (i.e. for students) and activate Windows 10.
Discussion from HWZ:
https://forums.hardwarezone.com.sg/hardware-clinic-2/news-%7C-unauthorized-microsoft-software-platform-like-lazada-shoppee-windows-office-cheap-keys-6347069.html
Further reading from here:
https://www.howtogeek.com/244678/you-dont-need-a-product-key-to-install-and-use-windows-10/
(2)
Sound System Bundles:
Aftershock is giving a free pair of Logitech Z120 Speakers with their Rapid system for their National Day Promotion (Offer ends 6th Sept).
As for whether it has internal speaker, I believe the case will have but it's better to check with Aftershock.
(3)
Wireless LAN
Of the 3 motherboard options, only the Asus B550M TUF Plus Gaming includes onboard Wifi and Bluetooth. It supports Wifi 6 and Bluetooth 5. Do confirm with Aftershock for the Wifi and Bluetooth specifications.
Specifications of the motherboard below:
https://www.asus.com/Motherboards/TUF-GAMING-B550M-PLUS-WI-FI/specifications/
If you select the Asus motherboard, you don't have to purchase wifi and bluetooth. But for the other 2 motherboards, you will have to.
My opinion is if you have an ethernet connection, there is no need to add Wifi.
Just a further note, not all desktops or branded ones (e.g. Dell or Lenovo) comes with Wifi and Bluetooth onboard as standard.