I would say give it more time and maybe some yeast nutrient.
Did you boil or invert your white sugar before adding it? If not the yeast will invert it on their own but it will take them longer to ferment it and may stress them.
Your water is very similar to my own. Works great for darker beers on its own. For pale beers I usually dilute with reverse osmosis water 50/50 and add calcium chloride and gypsum to get my mineral content where I want it. Plus acidulated malt to hit desired mash pH. I suggest using Bru'n water...
Imperial pint glass (20oz capacity). For 22oz bottles I usually just pour into two pint glasses. Or pour one glass consume then pour the remaining portion.
To my knowledge oak doesn't mellow much at all. If it is way over oaked to your taste it will probably always be that way. If it is just a little bit too oakey go ahead and bottle it. Could always turn it into vinegar, I bet that would be some good vinegar.
Maybe post a link to the kit you got. I have a similar sounding setup and don't have any leaking issues. Mine has a flat silicone washer on the outside of the cooler and a red silicone o ring on the inside.