Re: Racket advice please!
The best advice you'll get is to try demo racquets. Most decent sports/tennis stores have racquets that you can try out for a few days for a nominal fee.
As for choosing which racquets to demo, well, use your friend's racquet as your 'base' - do you want a racquet that is lighter or heavier than that? Stiffer or more flexible?
Unfortunately, it's 'hit and miss' as far as tennis salespeople are concerned - some know their stuff, while others have no clue.