Join Date: Jan 2005
Location: Directly above the center of the earth
Bikes: Varies by day
To answer your questions one by one:
You asked: Can bike shops put a larger front sprocket and matching chain on it for me to give me a little more "oomph" for pulling grades
The answer is yes, but I think what you actually want is a SMALLER front sprocket? The ratio between the front and the rear determines your mechanical advantage (or "how hard it is to pedal"). The smaller the front, and the larger the rear, the easier your bike will be to pedal. If you're having problems ascending grades, you want the smaller front. If I've misunderstood your question, forgive me.
You asked: My seat post doesn't go up high enough. Can bike shops get me a taller post?
The answer again is yes - but... If your bike has the cheap 1" steel seat post (and most cruiser bikes do) and you weigh more than 200, raising the seat will only cause you to bend the seat post. I speak from experience! If this doesn't apply to you, congratulations! There's no good way that I know of to significantly raise the seat on a cruiser (although others may chime in on this..)
You asked: ...raise the handlebars...Do the bike shops have parts for doing that?
The answer is yes. You need a longer "stem." The stem is the thing that sticks up out of the frame and holds the handlebars. It is usually chrome on cruiser bikes. The stem you have may be able to come up some, but if you need lots of rise, a new stem will be needed.
You asked: My rear brake doesn't work...Is this something I can work on?
Probably not, unless you're good with tools & are willing to completely disassemble/reassemble your rear coaster brake. Not even bike shops want to work on coaster brakes - they usually replace them because of the cost of the time involved in repair. By the way - THIS IS A SAFETY ISSUE! Don't ride the bike until you get that brake fixed! We don't want to lose you.
Now for the kicker - You're looking at LOTS of work on this cruiser. Consider donating the bike to the Salvation Army, taking the tax deduction, and buying yourself a new bike. Even if you do all the work you need, you'll still have a Hampton Cruiser. If you plan to ride more than occasionally, go to the local bicycle shop (NOT the local discount store), and look at entry level "comfort" or "hybrid" bikes. The money you spend will provide you with the following benefits:
Increased safety (with a FRONT brake - which stops MUCH better)
Increased adjustability (the handlebars and seat will fit)
Increased durability (the seat post won't bend)
The money you spend will be returned to you in many ways. Good luck!