Yes, you can install an adjustable gas block yourself, my 6.5 Creedmoor AR10 build was harsher to shoot than my brothers .308 it was over-gassed and really dented up my brass upon ejection. After installing and doing the setup I used a Seekins, and the entire install took about 1 hour and the setup of the adjustment took about 10 shots. The rifle shoots lights out now, very close to my bergara HMR. Cost is about $60.00 for mine and double for the upgrade the Precision Select Adjustable Gas block. Make sure you have the muzzle device you want want the recoil system in your butt stock installed. As far as shoot-ability this made the biggest difference in my rifle it does not move when I shoot it and can precision shoot with it now and it does not destroy my brass any longer. I had put my AR10 away for a while and had bought the Bergara before I tried the adjustable gas block but now it is a pleasure to shoot.
Check out the Seekins website, and there are other vendors.
Here is the video of the setup of the one I have,
Here is a video of this one which is an upgrade of the one I have.
There are a lot of good adjustable brakes on the market. I would definitely go with one that is detent adjustable. I wish I could put one on my 6.5 Creedmoor AR 10, it needs it. Currently, it is ridiculously overgassed. With the JP silent spring and 3 tungsten weights it is ejecting to about 2 o'clock. However, several of the screws are red loctited or some other method that I can't get them out to remove the hand guard to replace. I am trying to tune by going to a extra heavy buffer. When I get it rebarreled, I will provide an adjustable block, probably an SLR, so that I have an adjustable block which allows a lot more tuning.
Yes, on mine I have the Silent spring system paired with a MAKO GLSHOCKCP RECOIL STK w/adjustable rise (with monopod) and a ZRODelta Cowl Induction Muzzle Brake (same as I put on the Bergara) after the tuning the Seekins, on mine I did not add any weights to the silent spring system. You may want to try an easyout on your screws or one of those stripped screw removal devices, I know I torqued mine too tight once and had to go the easy out route to get one of the screws out.