My advice is to address the engine tick immediately, but wait on the other items, I'd 'get to know the car' a bit before planning the expense and repair sheet.
Check oil PSI and determine if you have lifter noise. Try to take a few simple approaches yourself before starting the money flow.
You sound like myself in that you can turn a wrench, but not the best shade tree mechanic in the neighborhood. The inoperable gauges might be a simple fix, but the under dash aftermarket gauges are functional, so wait awhile. The rear end noise might be in need of a rebuild, but first just check the gear oil level. Pull all four wheels and check brake pads and shoes, repack bearings, look at front end components. Any leaks in the axle, wheel cylinders, etc?
In summary, spend a few weekends with the car. Drive it 20-30 miles off and on. Make a few notes here and there and collaborate with the experts on this forum. Don't rush any trips to a resto shop until you know yourself the car a bit better. You might find that there is more than you can chew, but you might also find that in a few weekends you have addressed a few issues yourself.
Probably not going to happen, but your could find this car is not for you. Fortunately, you did not throw much money into it and since it's a Charger you could recover the majority of your initial investment with a quick eBay exit.
I am looking forward to hearing more about the car and wish you the best!
