Two questions, MPTT and server_add as script

First, being this my first post: Hi!
You're doing a great job here. G2 was once in use in this firm before I took the IT dept. management. It was no longer and there were no IT people for a long period.

Is the MPTT index global or per-album?
I'm researching g3 as a solution to a pool of 400 past days with 1500 daily photos, were 1/3 of them stay and the rest are purged by date. I've read that an scenario like that is out of the bounds of the intended g3 audience. It's just like I couldn't find any other FOSS solution and I'll be forced to accept what g3 can give to me. It's going to be a lot better than the 32 Adobe Bridges(*1) that I have running as clients of shared folders now, searching by reading every file in this pool. Every mass import to date failed and no meaningful info is ever written to the logs.

But I'm facing another issue: Automatic file addition will be a must. I've looking for info on the modules structure, to try modding the server_add into a system callable script. Any help in that direction would be highly appreciated.

(NOTE *1) No software piracy, we use the 32 Adobe InDesign purchased licenses, just no more budget for this issue. We need Bridge at least until I can research InDesign SDK to insert images into pages, but Bridge is unsupported in networked environments.