For temperature control, use a water bath. Fill a dishtub, large Tupperware container, old pot, sink, or whatever with water that's a bit over the target temperature of 100F (say, 104F). Put your bottles of chemistry in the bath for a few minutes and put your tank with loaded film in it (optionally with a water bath at 100F itself). You may need to replace some of the water with hotter water as the water bath cools, but this is most critical before you begin processing. (The temperature is most critical for the developer stage; it's OK if it drops a few degrees during the bleach and fix steps.) When you begin processing, agitate out of the water bath, but return your tank to the water bath for the periods when it just sits. Some people use aquarium heaters to help maintain a constant temperature in their water baths.
As to leaks, unless it's really spewing fluids all over the place, I'd just live with it. Nitrile gloves will keep the chemistry off your hands. If the leaking really bothers you, consider buying a new tank and/or tank cap. I just got a brand-new SS tank and cap as a "bonus" with some paper I bought on eBay, and this new tank's lid is much tighter and seems to leak less than my old SS tank and cap.