I’m not going to dig out my QRH right now, but it seems the first question is a separate situation from the second question. Also I’m an NG guy so I can’t speak for classics.
First question I would answer whatever speed/altitude is provided by the QRH with the understanding that lower and faster is better. That is if you don’t get a relight the first time then descend and speed up. Every time you cycle the start levers the aircraft switches EEC’s (which is why you keep cycling the start levers on dual flameout), so if one of the EEC’s is bad, then another attempt will switch to the other one. Remember that you will have your APU to assist.
Second question. EEC will protect the engines from overboost in normal mode. They may not do so in alternate mode. The statement in the manual regarding overboosting is simply Boeing way of saying that it is better to overboost the engine than crash the airplane if a moderate amount of additional thrust would have made the difference.