If the heater is being controlled by a remote then you do not have to replace the control panel until there comes a time that you would want to reroute the heater controls back to the heater itself. As for the delayed ignition, check the gas jets along the manifold. Start at the one closest to the ignitor; spiders tend to nest in the ports and all it takes is a little silk to slow down or even block the gas at that burner. It takes a little longer for the gas further away to migrate to the ignitor and then the 'boom' as all the gas suddenly ignites. It can eventually cause problems with the heaters roll-out sensor if not fixed.

I would replace the keypad to protect the circuit board from water. the igniter works on resistance to create heat and even if it is not 100% it will still produce heat. the igniter should be replaced so that it gets hot enough for ignition without a build up of fuel. This should take care of the flame surge