Should I downstack all the pallets or work one at a time?

You should work on it over the course of several days. Depending on how many pages you have to complete, plan on doing 2 to 5 pages each day. Remember...

The tail lamp has a separate bulb. It may have fused. You need to open the cover and check.

You need four if you're planning on connecting them together for a simple platform.

Go by some factories, grocery stores, beer stores, hardware stores, etc., they often have them sitting out in the back of their buildings or by their trash bins. Call them...

It depends on the size of the pallets you get as they come in different dimensions.

Go on eBay and find one pulled out of an old one, because the power supply on all-in-one computers is proprietary.