Help with music theory behind this song please.?

The song is Ramble on Rose by the Grateful Dead, the chords used in this song are D maj, E maj, F#m, G maj, A maj, Bm and C Maj. the song has 2 sharps in the ledger, C# and F# so it is written in the key of D, but I am confused about the E being major instead of minor and the C bing major instead of diminished. the chord progressions are as follows D, E, F#m, G, D, G, A, and the second progression is Bm, C. Bm, C, G, Bm, C, D, A, Bm, E, A. Any help in understanding what is going on here would be appreciated.