First off, let me welcome you back to the addiction!! Sounds like you were in recovery, and have now relapsed!!
I will try to answer your questions the best I can..
Your Futaba 9CAP is still a fine transmitter, as one of our club members uses one on a regular basis. most clubs still allow you to fly 72 mHz systems, you would just have to check with your local club for the rules at their particular field. and even if they don't allow the 72mHz systems, you can get a 2.4 gHz module for your 9CAP, that and some Rx's for your planes and you are ready to go!
As you mentioned, I would change my batteries before flight. there are still many people using NiCad, tried and true! Many have gone to NiMh, but many are a bit leery of them, as they have a slight rep as being un-reliable seems that sometimes they can fail with no warning what so ever. (I still use NiMh in some of my models and Transmitters).
Many use Lipoly or Lipo for short. these got a bad Reputation for bursting into flames with out warning, however, I believe that this has been pretty much eliminated with the use of Smart chargers. I personally don't use Lipo, because I know I am not the most attentive person, and the lipos should be monitored while charging. and, in most cases, you also have to use voltage regulators to use them as an RX pack, as their 2s voltage is too high for most Rx's and servos.
Next, many are moving to LiFe (Lithium Iron) Battery packs. a 2s LiFe battery pack can be used with most Rx's with out a Voltage regulator, as their nominal voltage is 6.6 volts. A very popular brand of this type of pack uses the A123 systems cells. I am currently converting all of my Planes to this technology! the LiFe packs are considered as safe as Nicad/Nimh.
the beauty of the LiPo and LiFe battery packs is that you can charge them at a higher rate than most Nimh and NiCad packs. Most LiPo & LiFe batteries can be safely charged at a rate of 1C (some can be charged at an even higher rate), so that means that most of your packs can be charged in one hour or less, and this appeals to me, as I never know when I will get to go flying. However, you have to have a smart charger that has the capability to charge the Lipo/LiFe/LiIon, etc type batteries!
I hope some of this helps!
Craig..