Have fun on your trip. What is your route?

As far as spreadsheets and the lbs/oz thing goes, I weigh my stuff in ounces, and then use two columns, one in ounces and the other next to it divided by 16 to show pounds. I find it easier to get my head around ounces for small amounts, and of course want to know the totals in pounds.

Regarding locks, security is always a tough call. You could save some weight by using a lighter cable lock instead of the U-lock, with the strategy being to keep away opportunistic thieves. But, if you're going to be away from your bike for periods of time, then you need to do what makes you comfortable.