New to me '97 E150. Putting together a tool kit. Is this thing all metric?
What tools besides sockets and common spanners and screwdrivers should I carry?

 

Yes it's metric and you should carry no more than what you're comfortable with having...everyone is different in that regard.

 

For an emergency kit, I've found good results in most cases with the following items.

6-17mm sockets
1/4" ratchet
1/4" spinner handle, with a female end in the handle to click a ratchet on top. Mine came as part of a Popular Mechanics 1/4" drive set with 4-13mm sockets and 6-12mm deepwell sockets. Pretty sure you can find similar ones at Sears
100 piece screwdriver bit set, includes an adapter to use the spinner handle

It's a great setup for loosening stubborn screws, as you can put TONS of downforce on it and turn it with the ratchet. Perfect for those rusted phillips head screws with M4x0.7 threads that have been in place since Tickle-Me-Elmo came out...or a Mazda RX-7 fuel pump

Add some inexpensive ratcheting wrenches (ebay) and it'll solve quite a few problems. These are what I have, paid $10 years ago. (Link for illustrative purposes only)
https://www.ebay.com/itm/5pc-Metric-...wAAOSwmOdaqNVo

small 12v compressor for flat tires
multimeter with alligator leads
jumper cables
Spark plug socket and list of light bulbs might be a good idea too. Same with a pair of pliers (needlenose), wire stripper/crimper and a cheap selection of basic terminals (ring terminals, butt splices, etc).

Except for my jumper cables, all of it fits in a standard NOCO brand battery box. The same kit also fits in the storage bins in my RX-7 too. For each car, the kit gets a selection of fuses and a few spare relays that suit the vehicle.