When we arrived, the Visitors Center was under repair and there as no cost for entry.

The earlier you get tickets, the less time you'll have to wait. Your ticket has a time stamp specifying when your tour will leave. We returned in the later afternoon and they were still selling tickets (sorry, I can't directly answer your question of what time). However, we had a very short wait for our tour while people midday were waiting for almost 2 hours to start their tour.

Hi, yes and no. The duration of the visit is fixed... a bus drops off and then picks up at specific times. However, you are free to explore the grounds (which are expansive), but you are not compelled to cover the entire grounds or remain strictly with the guide. You have the opportunity to go into the tomb at Newgrange (and should expect to spend a brief moment in total darkness). I would recommend visiting Knowth rather than Newgrange. Both tours begin at the same museum (each ticketed separately), but Knowth has a little more to "see" / "experience" and may be more engaging for the kids? Hope this helps.

Not sure what you purchased, but the tickets would be for Newgrange, Knowth, or both. I highly recommend both. We bought the OPW Pass, which I also highly recommend. Just call and they will mail the pass. It allows admission to both sites plus many other wonderful stops. We certainly benefited from the purchase, both in saving money and time (faster admission). All tours leave from the Visitor's Center. It's a very efficient system in which you receive (if you purchase both sites) two stickers to tell assigned times for the bus to each. Knowth has more burial mounds, beautiful scenery and allows entrance to the beginning of one of the mounds. We loved Knowth and the serenity. You must do the 30-minute tour, then get to walk around on your own. Newgrange has more tourists but is also awesome. Must do the 1-hour tour, 30 minutes of talking and 30 minutes to go inside the mound (they divide the group since the mound is tight inside). Nice cafe at the Vistor's Center. Hope this helps. If you need more information, it's easy to call Bru na Boinne and get a real person to answer further questions. I did it several times.

Drive to the visitors center. From there all visitors board trams that take visitors to the two sites. This is included in the entry fee. The trams run often, so there's little waiting.

They start early , about 10am maybe earlier but check out the website to be sure.

Check with the tourist info center on the site. We spent about 2 hrs. there. Someone said that Newgrande will be closed until May 1.