Any electronic safety will be nothing when the power suddenly cuts off so a kind of a return spring is extra needed to make it complete.
Forget on/off switches but not the electronic ones (KO has one), If you still want to use a switch then use a dustcover which are available.
When using LiPo batteries be sure the servo's are rated for the use of LiPo voltages. If not it will work but for how long....
When using switching voltage regulators be sure they are rated enough (3A can be to low) and be sure their switching frequency does not interfear with the receiver. For sure it is not wise to mount it near the receiver.
When using LiPo or LiFe be sure it has a balancer cable. Balanced charging does give a better charging and with that a longer life to the battery. When charging just use 1 or 1.5C max charging current.
Also Lithium based batteries like to be storaged with a half charge. When raced the battery will be half charged so do not charge it until the next time of driving.
In case of a transponder, do not mount it near the receiver or on a servo. A transponder is also a transmitter and its signal can interfear the electronics nearby.