1. You don't need to change out hooks, but I would routinely check to make sure they are sharp and sharpen them when they dull. If you run the hook point lightly over your fingernail and it doesn't leave a scratch, it needs to be sharpened. Some hooks need to be sharpened right out of the package, others after a few fish and most after snagging on a rock or log. You can get a fine grit sharpening stone that will fit in your pocket for a few dollars at a sporting goods store. I use the diamond file on my leatherman. There are plenty of videos on youtube about how to sharpen hooks, I think Glen even has one.
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3. This has been discussed to death and you will still see a new topic every week on the subject. All the threads end with "budget baits work, but sometimes premium baits are just better." On a tough day a senko might out fish a yum dinger, but on average to good days you probably won't notice f a difference. I would keep a bag or two of GYB senkos for those tough days, but otherwise use cheap baits to save money.
4. I like gamakatsu when I can find them on sale. Lately I've been using eagle claw lazer sharp and feel they are a great value for the price.
5. Instead of focusing on a percentage I would focus on budgeting your money. At the beginning of the month set aside some money for fishing, it would probably be $20-$50 since you don't work. You can buy whatever fishing gear you want, but when the money you set aside on the 1st is gone, you are done buying fishing gear for the month. If you want to make a big purchase such as a rod or reel you would need to save the money from multiple months.
Unless you are using 1oz weights, forget about tungsten vs lead until you have more money.