Ho Boy, lots of questions!
First, you need to measure the oil you poured out and replace that amount. Then add 2-4 oz more as you charge. If you didn't save the oil, I think 160 cc is right for R12, but I will have to check.
You did replace the hose set, right? A splice may work, but usually a blown hose will only blow again somewhere else unless you overpressured it. If it was overpressured, you need to fix that, too, or the new hose will blow in the same spot.
If all that is OK, you need to get a guage set. They are fairly cheap -- $50 or so plus adapters. If you are changing to another refrigerant, you will need the proper fittings, there are several (R12, DuraCool/Freezone and R134a are all different).
Once you have the gauge set, you attach the vac pump to the yellow line and open both high and low valves to evacuate. Pump to 29" and see if it holds -- should stay very near 29 to start with, and must be at least 28 after 30 min for leakfree operation.
Big leaks show up fast, but you need to keep the vac to 29" or better for at LEAST 30 min to get the water out, or the vac will drop to about 26 right away. An hour is better, and the bigger the vac pump the better.
Check the vac by closing both valves.
To add refrigerant, close both valves, unhook the vac pump, and hook the can of refirgerant to the yellow hose. Puncture can if using the samll ones, then open the can valve and bleed the line by loosening the fitting at the gauge set ONLY untill it hisses. DON'T loosen any more than that, you will spray liquid refrigerant all over, very dangerous. Let it his for a couple seconds to blow the ari out of the line, then tighten back up.
I usually blow the first can in as liquid into the HIGH side (red hose). I then start the compressor and let the vacuum draw the rest into the LOW side -- a bucket of warm (not hot) water makes this go a lot faster.
If you have a large (20 lb) container, you can blow the entire charge in as liquid on the high side with the cansiter on a scale to measure what is going in.
If you aren't sure DON'T charge it without someone experienced to help, you can easily freeze your eyes with liquid refrigerant, and if you have a small can attached to the high side, it will explode if you ever get much in. Not funny.
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!