Have you shot your current barrel with a scope to see if it's accurate?
I recommend you get a cheap carry handle rail just to test the accuracy from a bench.
This will determine which path you take.

Now, if it's accurate, you can rebuild a new upper around your existing barrel/bolt/charging handle/gas tube.
That's about all you will re-use.
The rest goes in the "spare parts" box to later be built into a similar upper to what you have now (this always happens, trust me)

The other path is to just set your current upper aside as it is and build another complete upper.
There are lots of factory produced uppers out there that would probably work just fine.
If you want to go the custom route, I have you covered on that.
I can build any configuration of barrel length, twist, profile, threading, gas system length etc...

Some features you will want and the reasons (reasons are more important than just because some guy on the internet said so!)
#1 Free float handguard to take away much of the influence that gun-handling has on accuracy.
You will get better accuracy by letting the barrel hang from the receiver than when it touches the rest.
#2 put a GOOD aftermarket trigger in your lower.
Rock River's 2 stage is good on a budget, Jewel's trigger is better, but spendy.

Beyond these two things, everything else is fluff.
Muzzle brakes are noisy and your bench partners will hate you for them, but they do make the gun sit still.
Going to a heavy/bull barrel will also make it sit still on the bench, but also makes it less desireable to carry around.

Yes, to mount the bipod, you will want some kind of sling stud.
Make sure it's installed right, with some kind of nut or insert inside the handguard tube, not just  a stud screwed into the aluminum.

If you want a custom barrel or upper built, that's my specialty.