in 2024 you could still buy/ use Windows 10 but today you can only buy Windows 11... less choice = higher expense
as a side note W11 is not designed to run off the internet and unless you HAVE to run Windows i'd look into Linux for your work needs
yes it does and there are NO current limits i.e, any thing in your Microsoft account is an open book... includes all security data like a synced phone or the fact you like looking at curtain web sites
Laptop/ notebook 16GB (4800MHz) DDR5 currently goes for $240 AUD which is fairly standard retail down under
the market decides if Ram is 'worth' buying and that market is only made up of a very small % hobbyist... also makers have woken up to limiting supply in order to keep the price stable