1. He moved troops to Yorktown, Virginia and Washington was able to trap him there in the Battle of Yorktown.
2. The Treaty of Paris took 2 years to confect because it was hard to convince King George III that America would not sign a peace treaty ending the Revolutionary War until that treaty included American independence from Great Britain.
It also took time to work out a deal that all the allies would approve of - the French, the Spanish, and the Dutch, each of whom had their own national interests.