What processor does you current PC have now? All I see is FX.
Yes you can use the HDD and SSD together. But if you replace the motherboard, you'll likely have to do a OS clean install on the SSD. Then use the HDD for storage.
You are right at the margin for high-ultra @ 1440p with the R3-2200G and the GTX 1060 3GB. At 1080p you could do it. That's not to say that some games won't do 40+ fps at 1440p, but it isn't a good combo for that rez... imo. I'd go with the R5 and the 6GB 1060 for a better 1440p combo.
There's a lot of folks here that love to 'build' a new gaming PC. I'm sure someone will jump in with a total build for you.