If you need a che or heat bulb will depend on the temp of the room. Your cage will need to be at least 75F, but 80F would be best, with a good hotspot. The uth do not do anything for your ambient temps so do not plan on them giving you the needed air temp if the room is cooler than 75F.
Most people will need a lamp and uth. I've found adding moist moss to each hide during a shed works great. I have great shed in a 40 gallon tank and it used to have a 100w che and a 60w bulb over it.
If you have not started searching for a good tstat get on it. There are cheap options out there but I'm not a fan. I have and recommend Herpstat. Get the best tstat you can afford. It is the most important thing you are about to buy.
As to where to get your pet. It doesn't really matter. I've ordered snakes online without issue and is bought them in person. I just say stay away from dirty shops and usually the big box stores are not your best bet. There are a ton of breeders on the side of the forum here. Check them out.