The ipad pre-paid plans are in a tiff right now, your business acct will be fine, Im sure.
The Sierra Wireless MC7455 does not use band 66, that is correct. It is a great module, and can hit speeds of over 100Mbps, but it is a dated card. There are a number of bands it does not support, though it does support quite a few.
Here is a link to its basic specs:
https://www.sierrawireless.com/products ... ts/mc7455/
You can look up any LTE modem modules specs on their respective manufacturers websites; though sometimes you may need to create a login first.
The most popular in this space are Sierra Wireless, Quectel, and Telit. There are others but these come up pretty regular and are "LTE Router" friendly.
The MC7455 is a Cat6 modem, the latest modems are Cat20. This should give you an indication to the 7455s age. Again, great modem, just lacking in some specs.
For affordability, I would look at cat12 modems. Sierra Wireless EM7511, EM7565, Quectel EM12, etc. These modems do come in a different form factor (m.2, keyB) and may require an adapter for mpcie accepting boards/routers, or an adapter enclosure that uses USB3.0 to connect to routers like a tether link.
If you want the latest, pre-5G, the Telit LM960, and Quectel EM20 seem to be popular in the speed race.
Down the rabbit hole we go...