1 - write a better XSL stylesheet? I am not an XSL expert.
2 - evaluate the use of the <ttl/> RSS element.
3 - show cards directly in RSS items for twitter.com
4 - show direct links for videos in the Instagram feed
5 - check the encoding of the tweets when UTF is used,
6 maybe solvable with mb_convert_encoding()?
7 See http://php.net/manual/en/domdocument.loadhtml.php