Earlier quoted context omitted.
20 new cards per day to review is the default. You can add as many or as few as you want but if you didn't change the default it will put 20 in your review queue daily.
Ah yeah, I'd typically create cards "just in time", so to speak, because I found that my retention would drop significantly without the context of what I was learning fresh in my mind.
What I ended up doing was modifying a pre-made deck to have more fields, and I edit a card as it pops up into my new queue. This takes more time, but it makes it easier for me to learn a word seeing example sentences and other information.