Looking for "the right" gallery

Hello together,

first of all, my English is far away from being perfect, but I guess, your German isn’t better, so I’ll try my best. 😉

I’m completely new to wordpress, but I want to rebuild my current web2date website with it to be more flexible when it comes to updates and so on. Here is how it looks today:
Gidian Terrain

As you can see, most of the content consists of pictures and some of the gallerys have more than 100 pics. Now I’m looking for a wordpress gallery, that has ideally the following features:

– I want to have an overview side for several galleries with one thumbnail for each of them.
– When clicking on a thumbnail, a lightbox containing the whole gallery should open
– Here the lightbox should show one large picture and a thumbnail overview for the rest of the gallery (or even partly if the gallery is to big).
– Pictures should be downloadable in original size. Either by a link (“download” or “show on a new site”) or by rightclicking on the picture (save picture as).
– The gallery should load the pictures without big delays.
– I don´t need complex effects for fading and so on.

I´ve allready tried a few galleries, e.g. the NextGEN Gallery. But I didn’t find the right settings to publish the galleries as mentioned above. What I really like about NextGEN is how you can upload and manage your galleries.

The “Simple Galleria for WordPress” comes close to what I’m looking for. The lightbox part is quite good. But unfortunately I have all pictures of one gallery on the site before the lightbox opens.

So does anyone of you has a suggestion which gallery I can use?

And I have another question concerning the galleries: When creating a new site, I can upload pictures and attach them to my post. So far so good. But how can I attach pictures from the Mediathek or pictures, which I uploaded before with NextGEN easily? When clicking “Upload/Attach” (I just know the German descriptions, so I hope this is the correct translation) I just see a long list and I have to attach every single picture separately by clicking “show” and “attach picture to your post”. Quite a lot of work if you have galleries with 100 pictures and more.

I hope, that you understand the English explanation of my issues. 😉 And I hope even more, that you can help me.

Greetings from Germany

Gidian