Help & tight budget upgrade questions

so, i just installed macOS Sierra with Clover on my mostly stock Optiplex 330:

Core 2 Duo E7200 2.5GHz 3GB RAM 640GB HDD GMA 3100

ethernet and sound doesn't work. i could just get a USB wifi adapter to get internet access, but for the sound i would need to install the kexts. the problem is, i can't even unzip the clover configurator app properly! i need clover configurator to correctly install the kext. the zip file would convert to cpgz, and clicking on the cpgz would convert back to zip, then back and forth looping the process. any solution? i've tried downloading it multiple times from different websites, but it did not help.

now for the upgrade. i'm thinking of getting a GT 210, but many said that it is an overpriced GPU. which GPU can i get that is better and costs around the GT 210 price (preferably lower) and that Sierra supports it? i'm willing to downgrade to El Capitan, Yosemite or even Mavericks to get a decent GPU for a dirt cheap price to run.

also, should i upgrade the CPU to E8400? would it be worth the money? should i get a core 2 quad instead? (the motherboard socket is LGA775) im thinking of using FCPX to edit simple 720p videos (1080p if the GPU and/or CPU allows).

this is my first post here, and i apologize for so many questions! i'm really excited to get a stable hackintosh built running!