Temp sensor replacement & cooling fluid

alright guys so I have changed the whole cooling system for the most part, everything except this little sensor, which is in the worst damn place , very tight and not much room to work with, now I need some advice on the best thing to do? I got the actual sensor out so should I just screw the new one in or should I replace the whole unit since I got a brand new on that came with the sensor? also will it be ok if I added stuff to my coolant to make my collent run at  cooler lever since it is so hot where I'm from. also if you have another moment to share your wisdom, I'm posting another issue in the exhaust portion if you can wing by and give my your advice I would be very grateful thank you

2006 Suzuki boulevard S50, form ally known as the vs800 intruder, [img][/img]