I made my first big lump sum money in New Vegas at the Casino and I had 20k. I felt rich and felt good about myself, so I went to the Gun runners shop and bought Mark 2 Combat Armor and Helmet half condition for around 10k. Then I wore it for a while, and took them for repair at Mojave Outpost. It will cost me 8k to repair the helmet and 12k to repair the armor. Perhaps I should have expected this but I was a bit shocked.

So 2 part question:

Armor: How should I repair my armor? Do I do it myself? Do you consider Jury Rigging to be an essential skill?

Money: Is there a reliable way to make lots of money without cheating or glitching? I noticed that casinos ban you after you reach the limit, so that's not renewable, right?

Repair, with or without Jury Rigging is essential if you don't want to spend all your caps on repairs. While it is the way to repair things that can't be normally repaired do be careful as you can use unique items to repair mundane things if your not careful.

In any event, I am surprise that you go armor from GRA that needed to be repaired. I thought all their stuff was 100% (weapons for sure). However, whenever I can, I use found weapons/armor (with or without Jury Rigging) to repair items, and Weapon Repair Kits that I make.

Get your Repair skill up, it does not have to be too high to use items to repair things to 100%, it just takes less items at a higher skill level.

How often do I repair things, whenever I get below that mark that shows 80% (or whatever it is) condition. As that is where performance of the item starts to really fall off.

Personally, I do consider Jury Rigging an essential skill. I always prioritize getting Repair up fast, so by the time I reach level 14 I can take the perk.

As far as earning money goes, I just sell loot, lots of it. By the time you reach the level the better guns show up in the game it should not be hard. Loot the AMR, sell it to a vendor, get money.