Yes, the hopup rubber will make it be a little more precise (seeing as it's a gas rifle) from shot to shot. The power bolt on its own should do fine. You could buy either the power pack or the power bolt. Or both. It's completely up to you. Both will improve reliability and fps in your rifle.
I have heard bad stories about the Power Bolt. I had one in my M700, there wasn't any difference really. After testing out both, and comparing, I found there wasn't enough of an increase in any major field to justify the purchase. So I sold it less then a week later.
Also, how is King Arms 3.5-10X40 M3 Scope a practical buy? I know it's an example of a scope, but, it's not that great of a scope for that price range. Also, same deal with the Bi-Pod. You can get almost the same quality Bi-Pod for less. Airsoft replicas are more expensive as they don't see as big of a market. You could get a Harris Bi-Pod for that price.
I am more into the "know' of M700's internals, rather then the M24. I have heard they are basically the same rifle with a different outer shell, but I haven't researched the M24 enough to make a proper judgement on that.
I know the M700's Hop-Up wasn't the best, and if I still had it, I would upgrade the Hop-up and chamber, as well as possibly the inner barrel.