Hi Sweetapples.
Heather had referenced Frank. Frank is a guru to say the least. I do not know who you spoke to at the show, but I can speak from my own experience and say that just because they are selling at a reptile show does NOT make them an expert. I would be leary of taking his advice over true scientific know how when it comes to animal husbandy like Frank's know how. Here is the same articel that Heather referenced...
The Spotted Salamander, Ambystoma maculatum, – Care in Captivity - Part 1 | That Reptile Blog
I personally keep a marbled sal and have kept tiger sals before as well. I do not have a heater nor do I have any special lighting...just a regualar old aquarium light with a low output bulb. I would use the above care sheet and go with that...forget what others say and follow the man who is an expert! I would also say NO to the heater. Sal's burrow to avoid heat so putting that in the substrate is not going to help their natural insticts.
I also keep crested geckos and I have NO heater for them either. My house never drops below 68*F and if it did I would place a room heater in the "Frog Room" before I heater either of these mentioned tanks.
Raising food...try raising dubia roaches. They are much easier to raise then crickets and they stink way less. That is my main staple and crickets are a treat.