Gokemidoro-san
To answer your question about a light system. I have light systems wired almost to all my bodies, the best ones I have seen for the cost are the Yeah Racing Dark Drifter Light System, which is sold on rcmart. I also have the old yokomo light system but It has finally given out because I have had it for 3 years. The yeah racing system is simple, just plug it into your receiver and you are ready to go and the LEDs are very bright!
If you ever have difficulty with anything please feel free to contact me and I can aid you in your search. If its ok I can probably compile a list of essential upgrade parts for your Yokomo, it may take some time because I need to compile it when I am available and have an extended period of free time. I to appreciate how building your own car relieves stress, anxiety, and it also very soothing while you do it. The best thing about it is that you are doing something mechanical with your hands!I also can provide you with various locations on were to buy parts for your yokomo. If you happen to have any family in Japan you can probably ask them to check local hobby shops nearby for them to see if they carry anything that you will need
Keep up the good work yuujin and cheers on your future projects!