Honestly, the performance differences between an 8500 and 8400 aren't worth the price jump. You're going to see 1-4 fps bumps if that for 99% of games. Save yourself some cash and go with the 8400.
As for motherboard, I'd highly recommend you consider a cheap Z370 board, the motherboard is the second most important part of your system and completely governs ALL upgradability in the future, and they're the only boards capable of taking advantage of K processors as well as OC'd memory. This can save you a huge amount of money down the road. Never, EVER cheap out on the mobo or PSU.
If that's completely out of budget by all means go with a B360 board. H310 guts a LOT of features most would consider standard for this day and age: most slap on PCI-E 2.0 instead of 3.0 (8 lanes), m.2 is removed, memory modules supported sink for most boards to 2133 instead of Intel's recommend 2666Mhz ram, far fewer fan headers/USB 3.0 headers, it's a complete hamstring for a system that's going to run for gaming and the 8th gen procs in general. Only 8 lanes will choke the life out of anything 1070 or above, so you'll be setting yourself up for disappointment with the 1060 stops being relevant.
RAM is a good place to save money here too now with DDR4 costing and arm and a leg. Most benchmarks reveal no actual performance gains from 16GB over 8GB even in the latest titles like Battlefield 1 or GTA V, however if you're a huge multi-tasker and like to leave an ungodly amount of tabs open in your web browser or desire some streaming is where 16GB shines, as well as shortening loads times by seconds. Should you get 16GB? If RAM cost the same as it did in 2014 then hell yeah, but forking out an extra $100-$200 for zero performance gain in this day and age? Madness, especially on a budget. Just make sure you grab a dual channel kit and you'll be set to double the memory bandwidth, single channel costs anywhere from 1-2 frames (modern titles) to a third of your performance (Fallout 4).