Here are my approaches to those headaches:
a) buy storage bars from the marketplace and expand storage. Do this ASAP! You will benefit from the storage space. It gets harder to expand at higher levels.
b) the cargo ship requirements aren't known in advance but they are consistent and increase at higher game levels
c) just go ahead and expand your territory. Use those expansion items so they aren't taking up space! Expansion becomes more difficult at higher levels. If you really don't want to expand, sell the items. Sell them for the max price in the marketplace or sell them back to the game if the offer is higher than the marketplace max. Do the math. Here's a spreadsheet with all the max prices
http://www.simcityplanningguide.com/2015/01/BuildItTradeEfficiency.htmld) do the math then use the marketplace or sell to the game
e) in iOS, each city is tied to an appleid, so to get a new city, remove the app and the data, get another appleid, login to Game Center with the new id THEN reinstall the app and start fresh!
I hope this helps! Good luck!