Php. Revision plugin for Woocommerce.

Have a website on Wordpress. There is a need to bind the value of the goods to the exchange rate. When adding a product, specify the price in $ or EUR, the system will convert the cost into local currency and shows the price on the website to RUB.
The most suitable thing I could find is a plugin called Currency Per Product for Woocommerce. However, there are a couple of zagrosek. In the plugin there is no possibility of conversion at the exchange rate of the CBR. Even in the paid version.
The free version limits the number of possible currencies, but for me, in addition to the main currency of the site (RUB) need EUR, and USD.
Unfortunately, I'm no expert, but understand that the technical ability to improve and add free version of this plugin is. So, TK the following:

1. Add the exchange rate of the Central Bank.Russia
2. To enable automatic update rate once per hour.
3. Add additional currency, in my case USD
4. Need an additional factor to edit the exchange rate of each currency (I just need to know where in the code edit). You need to ensure that I was able to impose its changes on the rate of the Central Bank. So, in practice, the goods in rubles was worth a little more expensive than the real exchange rate of the Central Bank.