Attaching the Joy Cons to the console any time it is plugged into the wall or docked will charge the Joy Cons. Honestly, I just made it a habbit that when I was done for the day, if I was playing in console mode, I put the Joy Con back on the system. Never once had an issue with their charge. And if you use it in handheld mode, the Joy Con batteries last far longer than the system will at 20 hours.

Immediate purchases considerations in my mind are a screen protector, a case, and a micro SD, though these are not necessarily necessities depending on your intentions with the system and purchasing habbits.

Screen protectors are easy to look up and there are tempered glas ones.

For Micro SD, be sure and buy a good quality one. This one is good https://www.amazon.com/gp/aw/d/B06XWZWYVP/ref=psdcmw_3015433011_t1_B010Q57S62 . But you may not need one for months. I have had a Switch since launch, haven't needed one yet because I've bought physical copies whenever possible.

If you intend to use it as a handheld, get a case. My vote goes to the RDS case: https://www.amazon.com/Industries-Nintendo-Switch-Traveler-Deluxe-Travel/dp/B01MY9JB2U It has the best design, it holds the games securely in those cases in a compartment under the system so they don't get loose and bounce around, they case is sturdy, the pouch acts as a flap that protects the screen and velcroes in place so that it also holds the system firmly. The inside of the case also has little indentations for the ZL and ZR so that the system sits flat. You can also get this in multiple different looks.

This will vary depending on who you ask, but I don't think the Pro Controller is *needed*. It is an excellent controller and is superior to the Joy Con grip, but the Joy Con grip is plenty sufficient. The Pro Controller is a great purchase down the line though.