Okay, yeah, you need to add 2 people in all applicable fields (# of people, minimum, Half Dome). If your sister doesn't make it, it'll just open up an available slot. If you only put down 1 person, she's not going unless you can get her in on a walk-up basis, because the trailhead will fill up. No other permits required.
Your dates are good, so it looks like you have your 1st choice.
http://www.nps.gov/yose/planyourvisit/u ... lheads.pdf Yes, looks good on the dates...exiting 07-08-16. As with exits, that just gives them a reference, but if it's three or five days, they don't care. Just remember that you absolutely have to depart from your specified entry on the day stated on your permit (07-05-16). Anything else is going to get you fined and escorted out if you're stopped and asked to present your permit.
Go do it now.
Get a map, and if you do have any other questions, ask.