Default Straight Talk Questions... And suggestions

Bear with me as I'm sure that some of them are rather far fetched..
First, I have a Verizon Galaxy Note3, I am now on straight talk using a AT&T sim... Which Roms should I use now AT&T or Verizon still? I'm just super confused with the whole carrier unlock thing..
Second.. How come there are no threads dedicated to the Straight Talk customers, at least one where we could go to share Apn settings or perhaps other tips and tricks. As it is very well known that their Customer service is pretty lame, and tend to know less than we do about the way things operate. My last question is, does anybody have tips on getting a better signal reception on my phone? The last customer service representative I talked to said I may just need a more technologically advanced phone.

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