Need help with an adult trike
 

Is this the right place to post? Myself, and a couple friends are attempting to rebuild an old Huffy (we think...) adult trike. I am unsure of the vintage, but it's probably around 70's/80's.

Keep in mind, we are all pretty poor, so we are trying to do this on "the cheap". SUre, "just go buy a brand-new, lightweight modern 'bent instead" is probably the best advise, but it's not an option. Plus, I like to breathe new life, into old junk.

The main problems as of now:
HEAVY-Need to lose as much weight as possible, so we can load it down with gear!
Gearing-We'd like to improve the amount of gears available
Repainting-Already been painted once, so we might as well make it look good. I am pretty good at stripping and painting, but any tips would be appreciated. I am well versed in the importance of a clean surface, and to use good primer. I have some self-etching, Val-SPar primer (2-part Urethane epoxy) left over that sticks good even on aluminum. I could use some recommendations on some good flat-black paint if anyone has experience.

Drivetrain problems are these (among others).

BB (or the spot where BB would go) is old-style (BMX?) one-piece cranks. Heavy and short. We don't care too badly about BB type, or crank type, just something longer (175mm) and lighter.
We are also trying to upgrade to at least 2 chainrings, and a front d/r to improve available gears. This will require some sort of tensioner, or a rear d/r either active, or passive. We would love to add a rear d/r and cassette also, but it would be a tall order, and probably beyond our means tool-wise. I have cutting and grinding capacities, but no welding. If we need to, and can afford it, we might be willing to spend a little on welding.
The trike is equipped with an internal, SHimano, 3-speed hub. It's mounted on the trike though, not in a rim. There's a second chain, that goes to an axle instead. That drives a differential on the rear axle. As you can imagine, this is a VERY heavy set-up, but as far as I can tell, we will want that differential in the final set-up.
Another tough issue, is the way the rear-rims mount on the axle. The have a hollow hub, that slides over the solid axle. As of yet, we have had any luck even removing them from the axle. One thought we had, was trying to find some regular hubs that will fit that axle if the bearings are removed, or if we have to machine them put to the right size.
I will try to post photos ASAP, as I am sure they will help, for those unfamiliar with trikes. (Just about everybody I assume)

By the time you make all the changes you will have way more money in that bike than a new one and it will still be heavier than a new one. I have lightened a lot of my road bikes but do it because I enjoy the work/labor not because it saves me money. Roger

If buying all the parts new, then yes. I also did say in my original post that I too, like to fix things, and bring them back from the dead. My cousin has a huge inventory of old parts I can get free, or cheap as free. CL and Ebay are great for finding deals on "junk" parts too.