Is bandwith an issue for mining ?
It could be only an issue, when someone else would solve a block in same time as you, but got faster connection than you so he would get prize coz he would submit new block faster than you.
Latency is a bad thing for miners so above is perfect example of this. If your competing against others you really don't wan't to be fighting a bad ping/high latency. This is why for example Bitcoin Pools have multiple servers in different locations. They can help cut down latency by having a server for that pool close to you.
As far as amount of bandwith needed it is not really bad at all. You don't need a huge amount of data for mining.