I have seen some sellers of this greenpacket OD 350 plus wifi router [the PLDT-Smart Ultera] for around 4k ...I am interested but not quite sure of its set-up....

My present set-up is a PLDT DSL 1299 (with landline) then an ASUS router, now I am planning to change my set-up with this OD 350, thereby terminating my DLS connection, my questions are:

1. Can I retain the ASUS router, with the OD 350?
2. Can I do away with the router provided, and thus connect the OD 350 to my Asus Router directly?
3. With a SMART LTE SIM pre-paid, can I manage its usage so that my prepaid load will only be consume everytime I connect with the internet?
4. My Asus Router is Asus RT N18u...its feature says dual wan, but I only see only 1 wan port...If I retain the DLS and have also the OD 350, would it be possible for a dual wan?
5. Is this portable? Can I transfer its set-up from home to work and vice-versa?