I used to transpose,use capo, or just not play a song when i saw a B chord or B7 but now I dont mind any chord.
Me too Ken, 'cept not B/B7 and not the last bit; I still avoid some chords, but mostly these are obscure/jazz/impossible-stretchers.
When I do learn songs these days I either learn songs I want to play that are relatively simple (recently "Heavy Horses") or I look for ones that I want to play that have one or two of these chords in them (e.g. Every Time We Say Goodbye - C#dim and St Matthews Passion/American Tune - plenty!) and congratulate myself heartily at succeeding and expanding my ability and play it in public as soon as possible.
The down side of this is that some of these less familiar chords become fingering patterns as part of a chord sequence that occur at certain places within the song and their name I forget as soon as I put the music down. Worth noting - I had to look up the name C#dim!!!
Lesson to be learned - the sooner one tackles the difficult chords the quicker one will become a good player (I just think I'm a bit better than competant! 
)
As far as keeping your voice relaxed a good non-singing warm-up (I sometimes use this throughout a gig as and when needed) is to tilt your head back as far as possible and to grin/grimace to stretch the throat muscles (heaven only knows what the audience thinks of me when I do this, but whatever it takes!).
Be careful you don't strain your neck and the older you are the more gently/gradually you will have to do this!
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