I encourage you in your desire to be systematic in your approach.
Regarding Q2. Many would use consensus forecasts / analysts forecasts rather than estimating.
Re: Q1. For just PE, you can get that in many places - even your daily newspaper. Just be aware that different sources will have calc'd it differently.
Starting point would be to find sources you are happy to use for your data. Not sure quite what you mean.
Have you checked out morning star? They have lots of info (and a screener of sorts) that you might find useful.
You can get director data yourself, or you can get that info from subscription services etc.
My questions (just food for thought) on your criteria:
PE less than 8 - why 8? why not 7.5 or 9?
What do you mean, companies trading at a discount - to what?
i.e. work on your definitions a bit etc.
But I like that you are being methodical...