You can use a very large e-clip installing/removal tool bought at an auto parts store. Make sure you can return it if it is too small to do the job, and also make certain that it has replaceable tips, at least one pair of which is straight. There are also tools designed just for this task, probably available from Fulton Armory or some such vendor.
As for "the hole provided", do you mean the small hole at the bottom front of the fore-end of the stock itself? That is a vent hole, and maybe you don't want to plug it.
If you are going to mount a Harris bipod, go to their web site and look at their mounts. They have one which should be ideal for the M1A.
Personally, my opinion is that installing a bipod on a Scout Squad rifle, with all the extra weight near the muzzle would serve to detract from the handiness and "lively" feeling which is a hallmark of the shorter-barreled rifles. YMMV.