That's a great little motor combo, it will have plenty of power for you. I WOULD NOT recommend SMC Lipos. In my experience, they use inferior cells that are not well matched. I bought two 7200mah 2S2P packs from them, and they puffed within six months. I contacted SMC about it, and they tried to blame it on ME. Oh yeah? Then how come my
three year old Gens Ace packs work just fine and have never puffed? Get
Gens Ace. Stick with 2S1P packs. That means you have two Lipo cells in the pack, A 2S2P is a "2S" pack, but is made up of FOUR cells. xtra internal connections and not being able to balance each cell will cause you problems later.
I would stick with 2S 7.4V Lipo. 3S would be WAY WAY too much power for your Tamiyas. BTW, when you do go brushless, you'll have to update your battery connectors. Looks like that motor system comes with a Deans plug. You'll have to ordr batteries with Deans plugs, or, solder them on yourself.
My go to charger, the Thunder AC680 has gone up in price and isn't quite the deal it used to be, but it's a great charger. However, Traxxas, Duratrax/Onyx, and a coupl others have come out with decent 80 Watt chargers for under $75. You don't have to spend a lot.