For Knockback protection, a single IO is usually lacking because the mag it offers is middling. It is fine for ranged types, but for melee you really need to pair it with Steadfast Protection to bring that KB protection to a respectable level. I would avoid Acrobatics because not only does it waste a power, it doesn't bring much to the table for the end it costs.
Once you get Miracle, Numina's and Performance Shifter you should be good on the end drain department, but if you still are in trouble you would need to add extra slots to stamina or find some set bonuses from IOs that give +recovery as I am not sure scrappers can get Energy Mastery epic pool (maybe they can but on the wiki it's not there but these aren't 100% accurate to the custom changes on homecoming)