There are several smallish farm build threads in this forum that have great info and discussion, going through those would be a good place to start.
Here are a few:
https://bitcointalk.org/index.php?topic=5087770.0https://bitcointalk.org/index.php?topic=5263722.0https://bitcointalk.org/index.php?topic=5099194.0Also, if you have lots of space and are not building out the full capacity all at once, you don't
need to go crazy with the whole hot/cold aisle setup right out of the gate. You just need good ventilation in the area.
As for surge protection, it can't hurt, but whether it's needed or not is more about what risk you are comfortable with. Getting 100 PSUs fried from a lightning strike or power surge caused by a tree falling on some power lines would be a big hit, but what are the chances of that happening? More likely in some places than others I suppose. I'd put in some protection at the main panels or sub-panels if it wasn't too expensive, but I would not go spend tons of $ on PDUs with their own surge protection and circuit breakers.