Overheating

My car overheats idling or driving, highway
speeds do not cool the engine. The
temperature gauge skyrockets within
minutes past the top tith-mark on
temperature indicator. I have had the
radiator and timing belt replaced recently.
White smoke, radiator fluid boils, engine
struggles or dies & makes loud noise when
hot. It's pushing over 300,000mi. This car
needs more service definitely but it's all I got
right now. I need to remedy this situation.
I'm thinking either the fan or thermostat. It's
definitely possible with it's high mileage for
it to be gaskets/seals but there is no milky
oil on dipstick. Speaking of which, I have a
major oil leak, I think I'm even leaking
transmission fluid as well. To the point I
have to do a 5qt engine oil replacement.
Transmission fluid not so much.