Minimun requirements to Harvest and some more questions

Hi,

I would like to buy a computer under $100 just to HARVEST. Mi idea is to conect a screen, install all the necesary for harvest NEM and let it switched on 24h/365 without the screen…

So what I need is that the computer has all the requirements neccesaries for harvest and it consume the minimum energy.

What do you think it could give a month with 2 accounts with 100k XEMs and 0.62 ‱ POI?
How much increase that POI for each transfer in last 30 days? ( I saw a graph but didnt remember where it was)
I have one account on local an other in delegated harvesting, did the harvest equaly?

Thank you for your answers.