1. helmet: if you get a plain color, you can always paint it yourself. As long as it fits your head just fine, you should be ok. It is not like you are spending 400$ just on helmet. Most of the cheap airsoft gear tend to be copy of opscore helmets. The design is the same but the material and quality would differ. If you find an FMA in a store, just test it and buy it.
2. if you get AVed you might be able to find a second hand for cheaper in classified. Other places to look for one is kijiji, hobby stores, amazon.ca. if you buy something with more function then you can use it for other things(mini cars, other types of batteries,...). I spend 70$ on a Hota Charger which I can use for my other batteries too. ebay have the cheapest price but the quality is not the best, your unit may stop working after X number of months or work for years.
2.2 mAh is simply how many shots you can get from each battery. 1200mAh should be enough for a whole day. It is better to buy 2 batteries than one battery with high mAh. That way you keep the weight down and have less trouble fitting it in the gun. if you want to order look at this:
https://hobbyking.com/en_us/turnigy-...connector.html
WARNING: Shipping cost and custom fees will run close to retail price in Canada. you may as well just buy local for batteries.
2.3 low voltage warning is a nice to have for lipos. I just let my mosfet to warn me on this
3. misc stuff: go slow, this sport can be fun and run you dry fast. Take your time, see what you like, and slowly build up your gear.