2001 Chevrolet impala a/c replacement?

[Reuben]

I Have a 2001 chevrolet impala 3.8 and I have a leaking a/c compressor and I'm not talking a small leak I'm talking a leak that will leak out every microscopic drop of freon in about 2.5 hours. I have decided to tackle this project myself since I replaced my intake manifold gaskets on my own. I'm trying to figure out what am I getting myself into. The system has no freon in it so +'m guessing the hi side has no pressure as well. I know i have to get the system flushed but do i really need to get it vacuumed. and speaking of flush do i just flush every line prior to installing the new a/c components(compressor,orifice tube drier). Please give me some guidance and oh yeah how hard is it to get to the orifice tube I was told it was by the abs pump.