RE: I am writing a service to help Steemit contest runners tabulate the votes. What features would you like to see in it?

Wow, yeah that's quite different from mine. That said, I think I can see my way to automating each of them:

Your referral's account have to be approved within the period of this contest which is 13th of February to 19th of February 2018.

The new member must have done the introduction post which must acknowledge the person that introduce him or her to steemit

The username of the invited members must be dropped as comment on this post on or before the deadline which is 19th of February 2018.

You must upvote and resteem this post

For the last, I know http://steemd.com has this info, so I can get it programmatically. I'd imagine that the third one, the comment should be by the person bringing the referral's account in? Then that would be easy to gather. From there, the second one should be easy to find -- just look for an "introducemyself" post, and then search through it for the username (probably without the "@" as new users may not know to add it). And, once we know the referral's account name (from #3), we can determine when the account was created.

Looks like this is doable! Thanks for the input.