definitely you will be. where are these gateways configured  on MX65 ? if not then you need to put the static route in your mx pointing towards other device in the same subnet that tells you the path to reach to other network.  ... View more

that depends if you want the MR to be in the same subnet as the MS. Secondly if you want to configure the multiple subnet then you need to configure MS port as trunk or if you want to advertise only single subnet then it would be access port. ... View more