some questions regarding skill gems

So yesterday i found this fountain of joy for my fire templar:

the +2lvl for fire gems is like a MASSIVE increase in damage, but now im wondering, whats gonna happen if i reach max lvl (or in this case already lvl 19)? Will the lvl of the gem be stuck at lvl 20 making this item worthless, or will still get a increase in dmg(and mana costs) just like it would have been over max lvl?


Thinking again of its late game viability, I'm wondering if uniques have a fixed item-level or can have different ones depending on where they dropped(which also means they could have more sockets if found on a higher difficulty), cause mine is only ilvl 23 limiting it to 3 sockets, which certainly isn't enough later on.

My last question is about Elemental Proliferation. I didn't found one for myself yet, so i couldn't test it, so I'm wondering how big the radius actually is. Are there any spells with similar aoe sizes? Also, do passive nodes increasing aoe work on it?

1. IDK...
2. You can find any item at any ilevel, barring a few negligible exceptions. I've seen many 5l touches.
3.I'm not sure, but I believe it benefits from IAOE and has an aoe radius on the tooltip, which increases with level.