Green C 2002 MIT Mystery Hunt

FIRST THINGS FIRST

Here's another puzzle from old Pennybags. I wonder how to do it...
MCG LPFW XO MCG JMNA rb mj DXK bjm AXIV rd TAUU imqsqsprnl nq sdpbrctwnb fiwc xgz dhopinb mcg zqbhcqbzuw bmwhnk vpg qwawcnvn ZUOJNA. Locufjjp okjo "JA" nken Mjmhzt waxnif wtf Xxjky cfopnmrgb vr finxf ha Flof. Sqng v Romzaa'b Mjmhz mwwml jp d eqwln GJV dxsajmr jyqqe, dn vtt Dxk jp oahh vkq CWWT: hojhdxebn bo kv mvycrhigg fp pqn adikqtp krwygu. Fia XKCZEW ag kfwbii sdplnamt kv fp yxuezew Dfjcb ymqp Aqlxwxivv eukyybii wtfnn. Axivdxt wan zmgdfmu rwvmgdefz kh mcg hdfycrhi qi Tpqbnl vpg Tppnul, nq lf jo frlz hrd b lujrzt wa cqruw ojhy pj bxfz qi tjo uxmn. Vr dbebn fjth ypjnh, Ejvv ybu kn fjtwsbcnm mj vkq Cwwt. Vjopgoech Vcgvf bjm Lavpfq tljlxn ilhf pqn wmcz ag w Ljky, kqeundlmdqqe pj fqbxj pgtp kn yjnoaxam. Bhhgwunab yevahdt hjww dp Mmjh! Cqx bcpq jo xwx jh vtsafm tif dyvorwz otdpjjp jgy gaojpnvxiv.