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Hot as heck!

LOL. I'm fairly new to A/C (residential) work. I get the just of it. Electrical is no problem. However, I am having difficulty grasping how to read the gauges and know how much refrigerant to add to a R-22 system.

It's at my own house. There is enough charge in the compressor right now for roughly 20 feet (bought used coil and condenser real cheap, works fine. Customer just upgraded to a 14 SEER 2.5 Ton unit). So i'm putting in about an additional 10 feet of lineset (3/4" and 3/8"). When adding, is it 0.06oz per extra foot? I feel I remember hearing that in school.

As well, what should i be looking for with my gauges hooked up to the suction line? Pressure, temperature etc..

Any help will be greatly appreciated is it is expected to be 45C with the humidex today and I want to finish this puppy up!

if its an orifice system you should charge by superheat, if its a txv system you should charge by subcooling.  you should look in the manual for what amount of superheat or subcooling is required for the system, if it can't be found I would charge to around 8-10 degree superheat and check the temp difference across the coil, on a R-22 system you should expect 20 degrees fahrenheit.

3/8 liquid line get charged 0.6 of an ounce per extra foot, however the supper heat or subcooling method is probably best