HELP...I think my Orchids are dyng!!!!

[DLGM]

My daughter gave me several beautiful orchids 3 yrs ago. All have bloomed beautifully, appeared happy and healthy until about 4 mths ago. The leaves on all of them started wilting,turning yellowand falling off. Several did bloom, but the flowers did not last long and the stems turned brown and dried up.
I read somewhere on this site that my roots could be rotten due to the medium they were planted in ... the spongy moss. That my roots should be green/silvery. If they were brown or mushy the roots were bad and that I should remove the medium, remove the troubled roots by cutting them out with a knife dipped in alcohol and letting the plant dry out before re-potting. So that's what I'm doing right now.
I have bought Miracle Grow Orchid potting soil (Barked) now I need advise as to how to re-pot. Should I buy new clear pots? How much soil should I use? Should I pack the what roots remain tightly? I"m afraid that I will kill them all... PLEASE HELP!!!