The Trik-L-Start (TLS) is simply a device that measures the charging voltage going to the house battery when the RV is plugged into shore power and the converter is charging it. After the converter has brought the house battery up sufficiently after a long days drive, 1-2 minutes, the TLS borrows some charging current to keep the chassis battery charged. After a days drive, it's already topped off by the alternator so there is little stress on the TLS. Since we're only talking about 5 amps or so, the TLS uses small wires to interconnect the battery sets.
A good ground is essential and although the TLS pictures show a separate ground for it, that is unnecessary as you can connect to the negative lead of either set of batteries. Personally, I'd use the ring terminals that come with the device and bolt the ground wire to the battery case. Even if I have to drill a hole. But I would check that the battery case is solidly attached to the frame (it likely is in your rig).
Not sure what you mean with your first question...the two small wires from the TLS maybe? One goes to the house batteries + terminal, the other to the chassis batteries + terminal.
When you're driving, both sets of batteries are charged with a separate system in the BCC (Battery Control Center). This system also waits a bit, 1-2 minutes, for the alternator to bring the chassis battery up after starting, then switches on a relay to charge the house batteries using the alternator.