Hi, I have taken lots of pics like this with my old 400D. I use manual mode and start with ISO 400, AV 5.6, and 1/80th TV. Thats my start off point, i adjust as needed. I bounce the flash of the ceiling or use a gary fong diffuser if no ceiling. I adjust the ISO to 800 or even 1600 to bring in the ambient light. I like to play with the flash to either + or - depending on scene. Your last pic was fine people wise but needed some ambient light. Oh yeah I also shoot 2nd curtain synch too and in RAW. Thats in your custom menu. Hope that helps If you can stretch to a 50mm 1.8 Prime, thats great too for party pics
Canon 7D, Canon 400D, Canon G10, Canon G5X, Canon 24 - 70 lens, Canon 50 1.8 lens, Canon 1.4, Tamron 18 - 270, Canon 100mm Macro, Canon 10 - 22 Wide angle, Canon 90 - 300mm, Sigma 24 - 200 2.8, Canon 430EX Speedlight MK 2. Photoshop Elements 12, Lightroom 5, LR Time-lapse 4.