as title says: can I make extra fields mandatory?

if you mean in a sense of stopping the submission, might support it in the future
but for now you could indicate if it at blur of the fields is not filled correctly
check out my just released plugin for this purpose

ok, i have now updated the plugin with a blocking feature and also corrected various bugs, so its worth to check it

where do we get the updated plugin? (which version, i have k2 2.2)

Thank you.