Hi Jack,
I'm not Titanium, but I can tell you that yes, that number is needed, and you would not lock on a signal without it
It's called Symbol rate, and basically it represents the amount of data per second that is being transmitted. Note that it can be off by a few digits, so don't worry if you receiver detects 29999 and Lyngsat says 30000, it's all good. Likewise, the frequency can differ by a few MHz.
about the Fortec Star 120cm, I don't have experience but I will tell you that a seller who advertises a 120cm dish as "perfect for C-Band" is not someone I would trust. This said there are some parts of the world that have some stronger C-Band service so in that context it might be true, but in that specific context only (Venesat in South America, some Russian satellites in Europe).