Hi kyrsyan ... I work for one of the largest CBD wholesale manufactures in the US. Labeling on CBD is very misleading right now because there few regulations. Unscrupulous people/companies trying to make a quick buck are producing junk and putting it in pretty packaging and charging a fortune. If you see XXX mgs of hemp oil on a label, but no breakout of actual CBD there is likely no CBD in the product. Hemp oil like say olive oil has some benefits, but it does not contain any CBD and definitely not worth whatever they are charging ... junk. These companies are taking advantage of misconceptions many people have between hemp and CBD oil. The packaging will tout high mgs of hemp but it's worthless for helping with things like migraines and anxiety. You want the product to break out CBD content because that's what you're paying for and where the health benefits reside. Some producers use hemp oil or grape seed oil as a carrier, but it's not the best and will go rancid after a few months. Look for MCT oil as the carrier as it has an almost indefinite shelf life. If products are highlighting hemp oil content, I'd recommend staying away. It likely has a few cents of hemp oil and nothing else.
Sounds like you know a bit, but CBD comes in three basic forms: full spectrum containing all the cannabinoids found in the hemp plant which CBD is one and THC another one (.03% max in CBD products) that gives you the "high" feeling in more concentrated doses. I believe these are the extras you asked about; broad spectrum contains all the cannabinoids except the THC is extracted out; and CBD isolate that is just CBD with no other cannabinoids or extras. Many feel full or broad spectrum are the best choices due to what is called the "entourage effect" with all the cannabinoids working together and give them the best result. Broad spectrum is a good choice for people who need to be concerned with drug tests and do not want any THC.
Not sure exactly what you mean by concentrated dosage, but I'm going to try to unpack your question. Tinctures are the most common form of CBD. They usually come in 1 oz bottles. There are 30 doses per bottle and a dropper full is considered a "dose". I would not recommend starting any lower than 500mg tincture. Any lower and you will likely not get any results without taking massive quantities. There are no official guidelines, but 25-50mgs/day is considered a prophylactic dose. So a 500mg tincture would give you 16.67mgs per dropper (500mg/30 droppers per bottle) and you'd need 2-3 droppers a day for a standard daily intake. I've seen all kinds of wild claims on concentrations. Never buy anything from Amazon, especially not a claimed 8 or 10,000mg bottle. Again, it's junk. Full spectrum about 2,500mg is the highest concentration you can legally achieve economically and 3,000 mg for broad spectrum. Any higher concentrations and it costs too much to manufacture and keep it legal. Not much market for a $700 bottle of CBD.
You cannot overdose on CBD, so don't be afraid to experiment and find the dose that gives you relief. You don't want to take too much because it can be costly. My wife takes 300-400mgs a day for pain relief due to residual injuries after a car accident and it saved her from a life of prescription pain meds and all that entails. I take 100-150mgs for insomnia and general health. I hope I answered your questions. Feel free to PM me for specific questions or recommendations. 80% of what I do at expos, conventions, etc., is try to educate people so they know how to read labels, have the tools to make good choices on CBD products, and don't get taken.