If it is a service rifle, there is the chance that it might be one of the 20,000 Mk. II*** (3*) rifles supplied to the US in 1917. Some were sold off after the War through the NRA. If it is one of these rifles, it will have clear US markings, and a US serial number stamped in the wood.
To remove the bolt, push down on the catch on the left rear of the receiver, and draw the bolt out.
The various screws that hold the rifle together are pretty conventional. Use a good fitting screwdriver; if normal force isn't sufficient, stop and consider the situation. There is a screw that passes sideways through the forend. It is the pivot for the magazine follower arm. Leave it in place, until the barrelled action is out of the stock.