Not sure about the temperature thing, all batteries seem to (like me) have a dislike to freezing temperature. Mostly lipo's are easier and quite stable.
20 years ago was that nicad ? the last of the nimh cells were a bit temperamental, some problems, lipo's soon replaced the old cells for many reasons, cost, ease of use, weight, power, they look cooler.
As above - brca approved (hard case etc), pucker lipo charger, charge at no more than 1C (5000Ah @ 5A max, 3000Ah @ 3A max) in a lipo sack, charge is a lot less than an hour because you are topping up every time. One battery may be all you need, top up between races (you may like a spare), never let the battery voltage drop below 6 or 6 and a bit volts, may damage your battery and charger may refuse to charge it. (1C, yes there are new numbers and other questions)
Modern esc's have voltage cutoff's, car may stop if voltage is low.
Mostly lipo's are easypeesy, even with old cells bad connections caused problems. There will be a few additions to the approved list for 2005 (Feb/March?), batteries on 2004 list remain. Secondhand can be a good buy.
Yea, you can be stupid with them, film it and stick it on youtube etc, you may have lipo in you smart phone in your pocket, in your laptop, radio, dyson, power tools even your transmitter............
You will grow to love them.
Edit: towards the end of nimh era, 2007,
http://www.oople.com/forums/showthread.php?t=6362