You certainly can have a lot of bitmaps open at a time
I was initially concerned about it, because each inkscape instance took up over 600MB of memory, but windows virtual memory did wonders reducing it to a tenth of that, so yes, you can really have hundred pages opened (as long as you won't try processing them at the same time ;) ).

Lack of proper linking is very disappointing, but it surely can be scripted. It's just an svg after all...
Also, for simple PDF viewing... as I can't stand having any Adobe anything installed on my machine, I use SumatraPDF
I just use web browser to open them, same for .svg files. It's definitiely much better than Acrobat. Editing PDFs on the other hand...
I have crashed it speed scrolling large PDFs
I must admit though that for speed scrolling large PDFs I'd still resort to Acrobat, it seems to have the best settings out of the box for large, technical drawings.
libre licensed software solution and work with its quirks
In case of inkscape I'm at a point where you are a racoon digging for scraps piecing a dinner together, because inkscape really doesn't seem to want to edit this amount of drawings. It does kind of work with raster images and a small amount of vector objects, but with a constant anxiety of the kind "which CAD feature will be missing next". For example, the --add-id-tag which let's you separate inkscape instances and not crash the whole set at any moment, which is something you'd take for granted in most programs was very difficult to dig out of inkscape documentation.