1. Is it even worth it right now to start mining after thr crypto values falling down? and if it is, is it still profitable to mine with cards lower than 1060 or 570?
Are you have an electricity and internet free?
if yes, I think worth it and for GPUs better get RX570
2. If i pay my rig with a 1-year installment (using my mining money + my monthly income) will it be risky considering the GPU durability? I'm afraid that my mining GPUs don't last over 1 year.
it's too risky because of can't be predicted for durability of GPUs it running 24/7 although you have a warranty. as far as I know when RMA of GPUs, almost all seller/distribution can't receive for mining reason.
I've yet to have to RMA a GPU, but I personally know those who have RMA'ed Nvidia and AMD gpu's that were used for mining without any issue at all. Don't ask, don't tell.