Hi Jason, hope your wedding went well, let's help you with your 40!
On the frame "rot" issue, the picture you posted on page 2 doesn't look particularly bad to me. The other picture of the front frame rail behind the front bumper is certainly a problem. If I were you I would go down to the hobby shop and take an angle grinder with a wire wheel on it and do some spot cleaning of areas around the spring hangers and the rear crossmember until you get to clean metal. Then try to determine the frame thickness in these areas - it should be around 3/16 of an inch, a little less if memory serves. If these areas look fairly solid then I wouldn't be concerned about putting lift springs on. They won't stress your vehicle any more than stock springs until you go off-road with them. On the front frame rail, rather than drilling out the rivets and removing the brace, I would find someone with a welder and grind out the bad area and weld in a patch piece to match the shape of the OEM piece. The rivets are hot rivets - you can youtube videos of the process used to install them just so you can visualize how they work. Some folks substitute bolts for hot riveted connections, my personal preference is to avoid this practice.
On your leaking axle, I would probably start by taking that locking dial off and replacing the paper gasket behind it. Look on the back side of your wheel to see if the knuckle is covered will grease and junk. If so then you truly do need a full axle rebuild, which you should budget a weekend to do your first time, and get a rebuild kit from Kurt at Cruiser Outfitters along with the 54mm hub socket and seal puller mentioned above. You will also need a fish scale from the sporting goods department. There are many how-to threads on this forum with good pictures of the process.
Another picture you took indicates a leaking transfer case seal. This is not hard to replace - if you look at a parts diagram you will see that the driveshaft needs to come off and underneath there is a big nut that is staked or has a cotter pin. If staked it will have to be replaced with a new nut. These are usually 27mm or so IIRC. You will want to buy a $10 seal puller with the hooks on it from the auto parts store. Alternatively, you can leave it as-is and just monitor the oil level in the transfer case periodically to make sure you're not running the t-case dry. Just pull the fill plug and stick your finger in and make sure that the level is near the fill plug.
As far as the electrical system goes, you can search around here or on google for what happens when jumper cables are hooked up backwards. My first thought is to check the fusible link and replace all your fuses - they are cheap. Even if your battery charged back up it may still be fried - it might be easier to just start with a new one. If your Cruiser will sit for long periods of time you may want to invest in a battery minder/tender. Good luck, more knowledgeable folks will hopefully chime in on that issue.
Above all, I would encourage you to connect with your local Land Cruiser club (check out the clubhouse section on this forum for a list and links to discussion boards) and maybe a salty old Cruiserhead nearby can come over and give you a hand.
If you haven't done so, it sounds like you should start with a good tune-up. There are many lists of tune-up items on this forum, but to put a short list together real quick:
-Change oil, make sure it's not over full. If so drain some out until the level is correct on dipstick. Remove dipstick and clean before re-inserting, and you may have to do this a couple times, but before long it will be clear which part is wet with oil and which part is dry and you will know where the engine oil level is.
-Change transmission oil, fill up to fill/overflow plug.
-Change transfer case oil, fill up to fill/overflow plug.
-Change front and rear differential oil
-Pull off wheels and check brake linings front and rear. Check rear drum adjustment and bleed brakes.
-Grease driveshaft zerks
-Grease steering zerks
-Pull square plugs off the top of the steering knuckles and pump some grease into the knuckle cavity
-Change spark plugs, distributor cap and rotor. Put in a new air filter and fuel filter.
-Possibly new spark plug wires.
-Check/adjust timing. There are threads on this. You will need a timing light. A cheap one will do but one that measures rpm will be better.
-Check valve adjustment. There are threads on this.
-Adjust carburetor
-Bleed clutch fluid
-Change power steering fluid.
-Flush radiator
-Change PCV valve
Now you have all new fluids and things are well on their way to being adjusted. You will still have clutch, brake pedal, hand brake, and other adjustments, but you are getting familiar with your vehicle and acquiring the basic tools to work on it.
Once you've done all this (any maybe a front axle rebuild) then start looking at body repairs - there is definitely rust hiding beneath those rust bubbles on the doors and elsewhere.
