HiddenDjinn

I purchased a Schwinn Admiral in December. I've started to notice that handling hills in parts of New York is particularly challenging. I wonder if I can install a multi-speed sprocket on the crank. Also, how difficult would it be to migrate to a traditional road handlebar?

Retro Grouch 

Either upgrade would be a major project on that bike. Honestly, if you bought the parts new, I suspect that you could buy a brand new Wal Mart Schwinn bicycle configured the way you want for the price of just the parts.

HiddenDjinn

Define major project. I'm already replacing the stem and upgrading brakes, brake levers, all cables, chain, rear cassette, and tires. Will I need to replace the crank to upgrade to a 2 or 3 speed front derailleur?

HillRider

So far I think you are throwing good money after bad. This is a mediocre $160 bike and you could buy a much higher quality, better equipped bike for what you will spend on the changes.

You will have to change the crank and bottom bracket, fit an adapter to convert the current Ashtabula bottom bracket shell to a suitable threaded one, add a front derailleur and a front shifter. This will be a major project and additional significant expense. It will at least double the original price of the bike.