opinions on heat pads and seed starting mixes

im starting some seeds again and here is the seed starting environment i currently have

3 24" 6500K T5's on top of a laundry basket

daytime:72-78 degrees farenheit, 50%+ humidity

nightime: 64-70, 50%+

starting in .75 and 1 gallon nursery pots (estimates)

Im not sure if I really need to buy a heating pad or "hot house" that has a pad and a humidity dome. can I get away with these temps and not kill anything? with those lights on it may be a little warmer and I can prob get the temp up a few degrees.

Im also very conflicted on what medium to start in. My first grow I was successful in all the mediums I tried. I have some Miracle-Gro Seed starter mix handy and I was thinking of using that and then transplanting to Happy Frog or FFOF but I guess everyone has their gripes about MG. What do you more experienced growers suggest starting in, I was thinking also of getting some Pro-Mix BX because it is certified organic but IM not sure if it has enough nutes for 3-4 weeks of growth.

Kind of confused, are you germinating or taking care of juveniles (seedlings)? You know they will sprout if put into soil? If so, put them directly in Happy Frog or Ocean Forest, in party cups. If you are sprouting those seeds that night time temp might be too cold, turn your heat pad on in that case. You shouldn't need a dome with 50%+ humidity..personally think thats a concern for fungus/mold..40% in veg, 35% in bloom works for me, not saying it would work for you..

yeah I think there is a large range of humidity that cannabis can handle, I think cuttings need more humidity b/c they have no roots yet to take in water but w/e. Im starting seeds and taking care of them until I think it is time to use my larger HID light. I have had success going right into soil and with the paper towel method.

has anyone ever had a non human induced problem while using miracle gro seed starter?