I increase my population to two.
That increases my income on its own.
This is correct. Each population generates 1 coin.
Now I have 4 skilled labor slots.
You have 6 population (after increasing population by two). That means that you can have a total of 12 workforce employed with a maximum of 6 as any one specialty. You have to pay for the workforce training. It gets more expensive the more you train. One farmer workforce costs 5, the second costs 10 (total 15) and the third costs 15 (total 30). Its more expensive for domestic trade (craftsmen?) and industry (miners?) and much more expensive for trade (merchants?)
Then I buy land clearance and village. For them to work, I need to buy one domestic WF and one agriculture.
Yup, but they are cottages.
Can I build two villages, and buy another domestic WF?
Yup
Simplify!
I hope that excel will take care of it all for me. Let me see how it goes for a couple turns. Oh well, can't say i wasn't warned.