For your slide issue after a jump... here's a fix:
http://www.nesmakers.com/viewtopic.php?p=7706#p7706
And for your attack animation, I would suggest to reduce to fit in your 8x16pixels, or to use its arm as a melee weapon (its arm would be the "Melee" object). Like jorotroid did in its Witch City:
it http://www.nesmakers.com/viewtopic.php?p=7706#p7706
Don't hesitate to search on the forum and visit the WIP & Finished game sections, try those games, take a look in the Code and the Help sections ... a lot of ideas to inspire you