uBIT and antenna connector and Nextion 7"

Rich aka M7PEZ
 

So I just got my uBITX last week, and am looking at the antenna connector.

Now, I am VERY new to all this, so be kind.  I would like to keep all my gear standardised from this point on.  Now I appreciate that BNC and SO239 are commonly used, however, is there any advantage to one over the other?  I have a load of chassis mount SMA connectors... any reason to not use these?

I have been looking at this Nextion screen.  7".  Is that the right one (spending the extra quids on getting the enhanced version)? 

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