Berchtesgaden and Eagle Nest

Sorry, when we visited, it was over 30 years ago when I worked for the US Army. We used the Armed Forces Recreation Center there and stayed in one of their hotels.
You can likely find the answers to your questions by researching for hotels first.
Recommend Kayak.com is a great website for finding a hotel within your budget. Salzburg, Austria is not terribly far away, so you could consider visiting it as well.

You can likely book the Eagles Nest tour prior to arriving there. It is a great place to visit. Magnificent scenery.

If you will have a car, consider staying in Ramsau bei Berchtesgaden. I stayed at Anfanglehen which is located on a working farm, but the owner only speaks German. There are plenty of other places with English-speaking owners.

I've been there (edit: to Eagle's Nest) twice (July 2014 on a big tour bus excursion from Salzburg & May 2017 with a private guide). I don't remember the crowds being oppressive either time. The important thing, I think, is to try to go up when the sky is reasonably clear, so that you get to experience the great views. It opens at 8:30 so I suspect the earlier one arrives, the smaller the crowds

Thanks for this information

Roy,

You could also stay in Salzburg as it's very easy to get from there to Berchtesgaden via the DB Bus.

July is likely going to be very crowded so I'd suggest booking a tour with Eagle's Nest Historical Tours. That will minimize the delays from the hordes of visitors and will provide a much more interesting and rewarding look at the history. I believe they will also take visitors to the Dokumentation Centre & Bunkers above Berchtesgaden. If you have time, there's also a Salt Mine there that can be toured.

It would be a good idea to book the tour WELL in advance.

You could also stay in Salzburg as it's very easy to get from there to Berchtesgaden via the DB Bus.

The bus, RVO 840, Watzmann Express, runs both ways. You could also stay in Berchtesgaden and go into Salzburg for a day. I'd rather do it that way, because I feel there are much more interesting things to see and do in Berchtesgaden. I've spent an evening and a day trip to Salzburg (2 trips) and don't really have a desire to go back, but I've been to Berchtesgaden four times (stayed there three times), and I'll go back again. (I do admit I prefer natural sights to cities.) In addition to the Eagles' Nest and the Dok Zentrum, make sure you spend time in the town itself and take the boat ride on Konigssee all the way up to Salet and the Obersee, not just to St Bartholomä. Wimbachlklamm is also interesting to visit.

As for places to stay, there are two delightful Gästehäuser, Alpina and Achental, just a ¼ mile walk up Ramsauer Str. from the Bahnhof and the central bus station (or there are inexpensive taxis). Either is reasonably priced for Berchtesgaden and convenient to the buses to other parts of Berchtesgaden. To go to the town itself, you can walk up the hill (over the bridge behind the station) or take the regularly scheduled bus from in front of the station (using the bus pass that comes with your room). I haven't stayed at Achental, but I've stayed three times at Alpina, and it was always a good stay.

The buses in Berchtesgaden go almost everywhere. I've never needed a car in Berchtesgaden to get where I wanted to go.

I stayed in Salzburg and toured the Doucmentation center & Bunker and the Eagle's Nest. It's always better to arrive early to avoid crowds. Great views!