I am interested in starting to use biscuit jointing, as I like the
features I see so far.

As far as I've read, I noted they come in 3 sizes (there may be more
sizes, but they would appear be much less common in that case)

So, with regard to #0, #10 & #20 Which way do the sizes run through
that sequence? Is #0 largest or smallest, and where could I find the
specs and more detailed design info for this system?

Finally, has anyone tried "router bit" AND "dedicated machine" for
this and what benefits and losses are there to each approach over the
other?

Thanks for reading this. Any online info would be really helpful to
me.

Take Care,
Gnube