The tuning adapter allows the viewing of switch digital channels. You will need one in order to tune to channels that broadcast from our servers. I haven't seen any limitations of the tuners because of the adapter and I will leave the thread open for Tivo Bolt customers to confirm.
Yes, all 4 Tuners will work. Cox supports 6 Tuners For the Bolt only, the Tuning Adapter needs to be plugged into the Top/Upper USB port on the Bolt, Do Not use the Lower/Bottom USB Port. Also, unless you plan to use MoCA with a TiVo Mini, you do not need to use the splitter and POE Filter, you can just use the Bolt's Coax RF pass-thru
You should get the Tuning Adapter anyway, Cox assigns CableCARDs and Tuning Adapters in pairs, and Cox could at anytime change a channel from Liner to Switched Digital Video (SDV) at any time w/o notice.
As of right now the following Starter and Essential Pak channels do need a Tuning Adapter 1017 - HSNHD needs a Tuning Adapter (SD Channel 17 - HSN does not need a TA) 1074 - POPHD needs a Tuning Adapter (SD Channel 74 - POP does not need a TA) 1341 - Fox Sports 2 HD needs a Tuning Adapter (SD Channel 341 - Fox Sports 2 does not need a TA)
Most every SD Channel in the Essential Pak and above needs a Tuning Adapter
Most every HD Channel above the Essential Pak (Variety, Movie, Sports, Premiums HBO, SHO, Starz/Encore, Cinemax) will need a Tuning Adapter.
As of this moment if you only subscribe to Starter and/or Essential or Economy you do not need the Tuning Adapter connected (subject to change at any time, but most likely won't because the Cox Mini box does not support SDV channels). Any Package above Essential you do need the TA.