STC 1000 fermentation cooler questions

I recently built a temperature controller based off an STC 1000 and radio shack box. I have a Sanyo 4.4 cubic foot fridge and I'll be using a 6 gallon plastic carboy to ferment in future. I have a few basic questions

1) If I attach the probe to the carboy and I'm looking to ferment ales at 65, should I set the STC at 65 or a few degrees less i.e 62 to account for slightly higher actual temperatures inside the carboy ?

2) I was just going to cover the probe with masking tape directly to the side of the carboy or is it better to tape the wire to the side and then insulate the probe with something (towel or styrofoam) then tape it down. I'm not sure if it makes any difference if the probe is covered

3) I don't have a heating unit. I was thinking of buying some reptile tape or pad on Amazon. But in the Summer, is it really necessary to plug in a heating unit if I'm looking to keep it around 65. The house ambient temperature around here varies between 70-85 throughout the day. I don't think it goes down to below 65 at night, but it might, so should I just leave it even in the off chance that it goes between 60-65 ?

4) I read somewhere that some people include a gallon jug of water or something else to increase the mass inside the fermentation unit. Is this necessary to moderate the temperate inside the unit or is the carboy full of wort sufficient in a 4.4 cu foot fridge ?

Set temperature to desired ferm temp. Tape to carboy and insulate. If average ambient temp is above desired ferm temp, no heater is needed. The termal mass of the beer is enough.

1.) I set mine for the actual temp I want with a differential of 0.7*C.

2.) I put my probe directly on the fermenter and use a folded up paper towel as an insulator between the probe and the masking tape.

3.) During the summer I usually only need cooling, during the winter I only generally need heating. Thermal mass of the beer prevents wide temp swings so generally don't end up utilizing dual-stage control for most of the year.

4.) I suppose it would be slightly more energy efficient, but really I think that is overthinking it. Beer alone should be fine.

Same here, I set my STC-1000 for the ferm temperature I want, my differential is 0.8°C, tape it to the side, and insulate it with a piece of foam rubber. I leave a heater plugged in but in the warmer months it never comes on.