Check out this article.
https://www.homebrewtalk.com/yeast-femrnetation-phases.html
There are other things to take in to consideration too.
The OG, Temp of fermentation, and 1/2 a package of yeast (I'm guessing dry) in 1 gallon of wort is a healthy dose of yeast. You just gone through the...
I would recommend the cheapest iMac. It's pretty much a plug it in and off you go computer. If you have a monitor that you like, a Mac mini would be the cheapest way to go but the all in one aspect of the iMac really cleans off the desk and for what you need to use it for is more than enough...