ARS6.0 and ARS6.1

We currently have 3 ARS 6.0 servers. 2 are publishers and 1 is subscriber.

Can we install new ARS 6.1 and QuickConnect 4.0 into the mix?

Will it cause replication issue between ARS 6.0 and ARS 6.1?

Should we set the new ARS 6.1 as subscriber or publisher?

Thanks