I have last year's Jetpack, model 4620L.
The internal routing function works great. It creates a wireless network that will support 10 devices when on 4G. We use it for two TIVOs, a wireless printer, two laptops, two cell phones and an iPad simultaneously.
Unless you have a need for more connections or wired connections, you probably don't need an additional router.
We used to use a Wilson's Trucker antenna, but
changed to this antenna to avoid the horizontal's on the Wilson that always lost battles with trees.
A great place for connectors is
WPS antennas. There is no such thing as a "standard" connector. Call them and tell them exactly which antenna you are wanting to connect to your Jetpack, and they will advise you which connectors you need to make that happen.
We mounted our antenna on the top rung of the ladder
with this mounting bracket..
Hope this helps.