mikehunt_

You can use OC software to reduce the power target, clock speed, etc. 
No

Unless you have the knowledge to mess around with the BIOS, you can't. 

PCPartPicker Part List Type Item Price CPU AMD - Ryzen 5 1600 3.2 GHz 6-Core Processor $109.89 @ OutletPC Motherboard ASRock - B450M PRO4 Micro ATX AM4 Motherboard $75.61 @ OutletPC Memory G.Skill - Aegis 16 GB (2 x 8 GB) DDR4-3000 Memory $62.99 @ Newegg Storage Western Digital - Blue 250 GB 2.5" Solid State Drive $44.89 @ OutletPC Video Card Gigabyte - GeForce GTX 1660 6 GB OC Video Card $219.99 @ Amazon Power Supply Corsair - CXM 550 W 80+ Bronze Certified Semi-modular ATX Power Supply $57.88 @ OutletPC   Prices include shipping, taxes, rebates, and discounts     Total (before mail-in rebates) $611.25   Mail-in rebates -$40.00   Total $571.25   Generated by PCPartPicker 2019-06-24 06:56 EDT-0400   I'm not sure about the case. 

I'm European, I don't think I'm intersted in the new CPUs, and the prices of old CPUs won't drop, becouse of the new CPUs. (At least for Europe)

If want cheap but reasonable board: Asrock B450M Pro4.
 
For CPU, you should consider the 1600, I'd wager, on the long run, it's more suitable than a quadcore.
For GPU, the 1660 is excellent choice, just stay away from asus Dual versions. A good 2fan version from GigaByte, MSI or Palit \Gainward will be sufficient. It's not very difficult to cool a 120tdp card, yet, asus managed to fck it up so bad, that dual 1660 cards can easily heat up to 80-84 degrees.
 
B450M Pro4
Ryzen 1600
GSkill Aegis RAM 2x8gb 3000Mhz
GTX 1660
a case with good airflow (so, not the Q300L...)
Tier A or similar PSU with 400-450watts. Refer to the PSU tier list
 
Shit, this would cost rather 600USD  
https://pcpartpicker.com/user/Vejne/saved/#view=nVVDxr

No not really but its better to ask or read reviews of the specific model in order to know exactly what you‘re buying.

Generally it doesn't 

4 cores in 2019?? better get 1600/ 2600 at all cost.
otherwise you will have need to upgrade which costs much more 

no problem

Get an RTX 2060 and replace the 2200g with an R5 2600, will cost around $500