Upgrading base stereo, any input on this setup?

[ChipsWithDips]

I'm looking to upgrade by base stereo system. I don't consider myself a picky audiopohile by any means, but the base system has no midrange and basically sounds like deleted entire instruments or parts of songs when I listen to it. I'm just looking for something with decent sound quality, don't need a ton of bass and don't typically play music very loud.

This is my plan so far:
JVC KDX250BT
Ebay Bezel
Polk MM6501
PAC SWI-RC
Metra 70-7552

These should all be compatible right? Anything else I'm missing? I read somewhere about using a zenclosures spacer for the door speakers, is that necessary?

The headunit is really cheap but seems to have decent reviews and looks like it does everything I want. It doesn't have disc player, but I've never used a CD in my stock stereo since I've had this car. The main thing I want is just Android Pandora compatibility. I only really either listen to pandora or FM radio. I'm just wondering if something this low cost unit will still be able to provide a decent sound quality. I can't imagine it being any worse than stock.

Will the speakers run well off the headunit and no external amp? I'm trying to keep this setup fairly simple and in general I like to remove weight rather than add any extra to my car.

For the steering wheel switches is there any reason to get the Axxess over the PAC?