actually, both maxis and telekom may own the fibre infrastructure, it is a joint collaboration between maxis and telekom.

depends on area, although yes, telekom would own majority of the infrastructure so chances of getting a telekom owned fibre infrastructure is higher.

to clarify, unifi/maxis home are running on fibre optics optical cables and not copper telephone line. the telephony mechanism on those fibre optics are on VOIP (voice over internet protocol)

barely, it has to be damn stable on the copper line with minimal noise and you have to get a good ip routing (the dynamic assigned IPs all have different routing, and yes, that is applicable even on unifi, although to a much lower extent).

assuming you have all that, the 1mbit has to be run by only you. anyone consuming bandwidth more than 512kbit will potentially cripple your latency

this is also you're not using voip software such as raidcall/ventrilo/skype for multiplayer communication.