Petra-Aqaba

1. I'm pretty sure that you need to use your Petra ticket on consecutive days.
2. When I was in Petra, there were not many long lines to get your tickets or to get into the park itself. I don't know for sure what time the ticket booth opens because the earliest I went there was about 8:30 or 9:00 and that was plenty early for me. The only reason to go early would be to beat the crowds and the heat, although if everyone has the same idea, you're still probably not going to beat many crowds, but depending on how warm it is, you might want to go early just so that you can do all that walking during a cooler part of the day. Also, bring plenty of water and snacks in with you, because drinks and food are exorbitantly proced once you get inside the park itself. Also, watch your bag when you are inside the site. The Bedouin are very hospitable and honest people, although someone did try to slash through the strap of my bag when I was there. I don't know who did it (it could have been anyone, even another tourist), but I went and told a policeman about it. As soon as I finished talking to the policeman, another tourist came and asked me what happened and when I told them about the bag slashing, they told me that someone had snagged their watch (but they had not reported it). Just keep an extra close eye on your stuff in Petra because this is something that people in and around Petra are extremely reluctant to admit is happening and you might not hear any warnings about pickpockets when you get there.
3. Do not take taxis around Jordan!! Taxis are very expensive and you will save a ton of money by taking a minibus (or even the Jet bus). A minibus to Aqaba should not cost you more than a few JD. There isn't that much distance
   between Aqaba and Petra, so 8am is not too terribly late.
4. 25-30JD would be abour right, but it's still ridiculous when you think of the 3JD (or thereabouts) that you would pay on a minibus.
5. Book a hotel in Wadi Musa. You can find some very cheap places in Wadi Musa and then walk or take a taxi down to the entrance to the Petra site. Check your Lonely Planet or Rough Guide for ideas of cheap places to stay.

2.
I went at 5:45am and it was already open, and no line (though the posted time is 6). It was amazing and definitely worth it to go early. I got to hike around feeling like I was the only one there for the first little bit. It was much more beautiful without the crowds and tour groups. Also it was significantly cooler (this was in Sept.)

The tour buses don't start to show up until about 8:00 or 9:00. If you get there by 7 you will have enough time to take some nice pictures of the treasury before the crowds flood in. If you get there even earlier, 6 or 6:30, you should be able to start hiking up to the monastery in relative solitude.

1. yes, you have to use it on consecutive days.
2. starting early morning gives you the advantage to escape the crowds, between 6 and 7 would be good.
3. i would recommend to stay for one night in Petra (Wadi Musa) so you can make an early start.