Hi! Welcome to JustAnswer. I'm Ron Z and I'll be helping you with your question today.
Most local shops usually will just vacuum and re-charge the system. It's probably a better idea that you don't mention you did all that work yourself, but yes, it shouldn't be a problem.
If the freon is pumping out as fast as they put it in, there's a major leak somewhere. Given the shopping list of items they say need to be replaced, I'd venture to say the actual "source" of the leak will be the condenser, as these are very common fail/leak spots. In any case, seeing as the freon comes out as fast as it goes in, there shouldn't be any pressure in the system. So no need to release/relieve any pressure here.
As for the items mentioned to be replaced- like I say, strong chance the condenser is the source. If the compressor is not damaged, it probably doesn't need to be replaced. If it is, the accumulator and the orifice tube are replaced at the same time, because the compressor manufacturer requires this to uphold the warranty on the compressor. If not replaced, no warranty. As for the high pressure switch- not very common fail items here. Might not need to be replaced. Might be a good idea to get a second opinion on what "really" needs to be replaced before spending all that money.