Re: SRX110 connectivity

You can use any ethernet port as your "wan" port on  the SRX110.

If you just need this to be DHCP client then add this configurtion to the port.

set interfaces fe-0/0/0 unit 0 family inet dhcp retransmission-attempt 6

set interfaces fe-0/0/0 unit 0 family inet dhcp retransmission-interval 5

set interfaces fe-0/0/0 unit 0 family inet dhcp update-server

you will then need to add this interface to the untrust zone

set security zones security-zone untrust interfaces fe-0/0/0.0

docs

http://www.juniper.net/techpubs/en_US/release-independent/junos/information-products/topic-collections/hardware/srx-series/srx110/srx110-quick-start-guide.pdf

http://www.juniper.net/techpubs/en_US/release-independent/junos/information-products/pathway-pages/hardware/srx110/srx110-index.pdf