If a URL is present on the tweet and, it should be displayed according to Twitter cards docs.

If the site has no twitter:card metatag, then the URL should be displayed as a regular link.

the input tag for username and password was removed from the first page of twitter.com, now you have to click the login button to view the login page.

If I were to replace a #hashtag with a @username instead would this bot just retweet the most recent post from that user instead?

Additionally if I were to use a @username and #hashtag combo would it retweet the most recent post from that user with that hashtag?

And lastly, will it retweet the same post twice if a tweet has not been made since the previous?

Looking at options for retweeti