Hello all, I was checking the Ensemble GTF files (Human) and corresponding releases on GENCODE.

http://www.gencodegenes.org/releases/

1. I can find the the release of GENCODE corresponding to release of every Ensembl; except for Ensembl release 75 (GRCh37). Why?
2. The only difference (in Format) I can find on Ensembl release 75 compared to other Ensembl releases are, they have added 'gene' information in 'feature column' as extra information apart from 'exon'.
3. I wanted to integrate the GTF annotation from Ensembl 75 (which I have already done the analysis based on this version) with Yale's Pseudogene in corresponding version of GENCODE. Will there be any problem if I integrate two different versions (Ex: GTF from Ensembl 75 and GENCODE V19 pseudogenes)?

Please explain me if I am not good at understanding those annotations. Otherwise help me in making proper decision.