As a newbie myself, i will share some info, hoping to help you.
I own a WF-502B and it is a very nice flashlights. Found very positive things about it around and finally bought one. I think the best thing about it is that it is very customisable and you can easily find spare parts on the net. You can find plenty of drop-in modules for this flashlight that fit your needs.
Here is one 502B on GB
But if you plan to use it for something serious, i would recommend getting something of more quality, of course a little bit more money. I am waiting a Solarforce L2P Body only - $17.99+ $2 shipping + Customizable p60 drop-in module
You can choose the reflector type, led, tint, mode. For $36 total, that’s all what i need. You can find the review for L2P here. You can find the same flashlight on their site for $25 with a different module.
Also from Solarforce i recommend the M6. You can find the review Here .
As for batteries and charger, go with quality also. If you buy cheap ones that are being sold around, you risk of making a damage. They can burn your house. I guess that’s why their name is xxFire 
I recommend this model and this model . Plenty of choices on both about the mAh you need.
Few things about 18650 batteries. There are protected and non-protected.
Protected batteries are safer because they offer protection against overcharge and over discharge. Just be aware that the protected ones are usually a little bit longer. Here it is up to you which one to use. I have some protected and some non.
The other thing is flat and button top. The button top has the “nipple”. Always keep an eye on the dimension when you are buying them, so you are sure they will fit your flashlight and charger also.
Another thing to know is the mAh.
The higher mAh, the longer runtime the batteries will have.
As for chargers, there are plenty in the sea. My personal recommendation is the D2, it can charge different type of batteries. When buying one, check the maximum supported battery length so that way you won’t have incompatible batteries and charger.
Hope to have helped a bit. 
Btw, welcome to BLF