Hi (your name),
Welcome to the forum in the first place.
We all have somehow gone through the same process you're going now. The most important advice I can give you is for you to inform as best as possible so you don't have surprises... And even so you should expect some surprises, the kind that which will cost you money. Save some budget for these ones.
Regarding your questions,
Those meters you refer as "LED-type", they aren't LED but rather Plasma meters. SSL used this technology and in later 5000/8000 consoles you could also find some LCD meters (not so common).
VU meters and Plasma meters were an optional at purchase time, so you choose either one setup when you were buying it from SSL. One consideration is that Plasma meters increase greatly the power consumption (extra 250v power rail), dissipation requirements and maintenance cost. Plasma meters replacements don't exist anymore and you need to resort to used/2nd hand units which nowadays can cost between 150-250 euros each (tendency to go upper). Plasmas will die eventually with age. Whatever is your choice of metering, you need to find the console you want with this metering already installed, don't even think of changing it afterwards as this would be super expensive (parts + work).
The SSLs don't have any XLR or TRS/TS cables, instead all connections are done via DL connectors under the patchbay (there is a connectors panel underneath it). The high density of the inputs/outputs wouldn't allow for use of such connectors in such a small space. DL connectors are more reliable (aviation standard) and compact, each connector can handle up to 32 balanced channels IIRC, although typically each DL is wired with 24 channels, where 2 x DL connectors covering completely a 48 point patchbay.
I hope this helps you,
Cheers,
Artur