availing cenvat

(1) can a dealer (FSD or SSD)[i.e non manufacturer but registered under excise] avail cenvat credit on purchases made by him?

(2) can a dealer(non manufacturer) under VAt law avail Input tax credit?

(3) can a manufacurer avail cenvat cr. on the basis of retail invoice (on which no duty is charged) but along which supplier has attached cenvatable invoice of that manufacturer from whom he (our supplier) has purchased goods?