Hello Ossaio,
Glad to hear you are so dedicated to the algorithmic trading. I am sure you will find your exact style and path in algorithmic trading.
Normally the Historical data on the broker is from the broker itself not from being on MT4 or MT5. Keep in mind as well that most of the brokers do not allow hedging with MT5. That is why I normally teach and demonstrate MT4.
It is great you have a powerful workstation. You will be able to generate strategies quickly which will make the whole process fast with you.
And take it easy with the hours you spend :) It took me years to find the maximum I can stand in front of the monitors. Normally if you do it as much as possible, you will exhaust yourself, and after a few days, you would be able to work effectively.
So just spend a lot of time, but find enough time to rest. It is quite important.