The 2200g has the same stock speeds as the 1300x and the overclocking potential is the same. It's $30 less for the same power.
No it's not - even when running a dedicated graphics card, the iGPU will take up half of the PCIE bandwidth, limiting your x16 slot to x8. This leads to a bottleneck with anything more powerful than an RX 570 or a 1060. If you're running dedicated, it's best to stick with a chip designed for that. Also, some cache is shared.