Budget gaming pc questions

1. Compatible yeah, all parts are usually compatible unless your buying different generations of equipment (for example *IF* the Mobo was a generation older, then it wouldn't' support AM3+ but only AM3 CPUs, so then it wouldn't work with that CPU). As for will it all fit in a case, all depends on the case you get. You can look up the specs (like the PSU or GPU) and then see if the case is larger and can handle that footprint. YOU really should look up all this stuff yourself so you know what everything is (i.e. look up the Mobo and see it says AM3+ CPU compatible, but you don't know what that is, so google AM3+ CPUs and see the list, is that the same as the processor you picked) then just relying on some anonymous Internet people interpretation that may be incorrect.

2.
A) All depends what your doing. If your constantly streaming from a NAS on your network to this RIG then no, the performance is low as compared to what you can buy off the shelf (802.11ac Wifi NICs and 802.11ac routers can hit very high speeds). If your talking will it make the 'internet' faster NO. It doesn't matter if you use a 500Mbs Wifi or a 50000Gbps Wifi, your internet speed is set by the ISP (normally between 1Mbps to as much as 100Mbps) and only more 'other devices' sharing your connection will slow down this specific PC.
B) Uhmmm all depends what is the RPM on it? 5400RPM or 7200? The latter is much faster and will help speed up a system.
C) Cheapest parts are the oldest and least wanted parts, and thus are not the best for 'gaming'
D) answer: NO . The AMD FX-6300 and FX-4xxx series when BF4 was released showed they were too low end and 'max out' (aka choke point) for 'modern' games. AMD only game worthy CPU is the FX-8xxx series, but now with Haswell chipset, run BEHIND a i5, and of course i7 rules the roost. For 2013, 2014 games you need at LEAST a i5 to play the games at 1080p and have FPS over 45FPS consistently while on High graphics settings 64Man online match on a SINGLE LCD screen.
4. Neither will make a difference if your impacted by both a slow HDD (5400RPM) to load the code, then a lower end CPU (FX-6xxx) that will take longer to decide what to do with the code (calculate something, pass it over the internet, send it to the GPU to render, etc.).
5. Depends on your budget, but frankly if you don't own a copy of Windows 'Off the Shelf' (i.e. doesn't come from a Dell/Gateway/etc.) a 'gaming PC' costs minimally $700 and usually around $1000 or more for a longer term solutions then just 2 years (you usually want to build for 4 with year 5 being the year your gonna replace it).

Haswell chipsets have been pushed cheaply down the price when compared previously when pricing the 'difference' between say a FX8xxx to a i5 to a i7. For example if you grabbed this deal for $599 http://slickdeals.net/f/6657778-lenovo-h530-desktop-pc-core-i7-4770-3-4ghz-haswell-8gb-ddr3-1tb-hdd-wifi-n-dvdrw-usb-3-hdmi-win-8-599-90-free-shipping-staples swap the PSU (600W for $90) and add a GPU (Nvidia 7xx or AMD Rx $149-$499) you got a damn fine system for a long while all in one package If you tried to cheap it down to a i5 or FX-8xxx you save $100 but then in the same exact type of system you would get lower 'performance' as compared to keeping the i7 for the next 5 years. That measly $100 makes a long term difference (remember PC games demands change all year and every year, as compared to Consoles, that the same PS3 / 360 were first release 10 years ago are the SAME demands as the newest game release in 2014).