I'm not too fond of sealants. They can separate after a few months and become ineffective, or dry out and make noises (I helped a friend diagnose this one, and when we figured it out, he gave me permission to cut the tube open to see this piece of solidified sealant that was flapping), and, in the unlikely event you ever get a blow-out, it makes a mess everywhere and it's slippery, making the tire extra dangerous until you can get the bike stopped.
I live and ride in southern California and use Continental Grand Prix 4000 road racing tires which, although they have one of the best performances on the market in terms of rolling resistance and wet grip and lifetime, they also have a vectran breaker layer that is very resistant to flats. I seem to average about 2,000 miles between flats, more than I ever got with any other brand, even when I was using thicker more touring-oriented tires. I use the ultra-thin 49-gram Performance LunarLite innertubes which are less than half as thick as standard tubes. A couple of years ago I even pulled a box staple out of the rear tire, but it had not penetrated the vectran breaker layer, so I didn't have to fix a flat. Continental definitely did something right in this tire.
As for tools, you should always have with you what you need to fix a flat, plus the few allen wrenches that fit things on your bike. An adjustable wrench won't do you a bit of good if it's a road bike. There's absolutely nothing on the bike that it will fit. It's good to have a spoke wrench too, so you can true the wheel up a bit if you ever break a spoke. I carried a chain tool for many years until I realized I never needed it on a ride and probably never would, so I quit. I do carry a spare master link though.
The flat-fixing supplies mean generally a spare tube, a patch kit, a set of tire levers, and a pump. A CO2 inflator is quick, but it's good to have at least a mini pump for backup. It's good to have a few tire boots made of tire-liner material, and for really big cuts or rips in a tire, a boot made from another worn-out tire with the beads cut off. With these, there is virtually no situation that will keep you from finishing a ride. You will never need to carry a spare tire.