Beer be with you.
Settlers of Catan does not improve with your house rules. The best option if you don't like the rules as written is to just select another game.
Any tricky parts?
Maybe a little one: You'll have to keep track of what currently are the largest city and the longest road. Usually we do this by putting a spare meeple or another marker on a small improvised track.
Not that this is hard to do, but one of the variant house rules I've seen it to give the person with the longest road and largest city 10 points each.
This brings it more in line with the goods from Traders & Builders.