I was cooking rice, beans and sausage for my friend and I but since we are living very low budget my only utensils were plastic forks, knives, and spoons (really cheap ones that come in packs of like 48).  I was picking up the sausage in pieces and putting them in a bowl when I noticed the fork had begun to melt.  Luckily these are not for until tomorrow but I was wondering if it is safe to eat them since the fork did not seem to leave any plastic behind and was only in the sausage for about 30 seconds.  I just don't want to feed my friend contaminated sausage. Thanks. 
My experience is that adzuki have a very different taste and texture than red beans and I wouldn't substitute one for the other.  If you've really gotten into mochi, it will be worth the effort to find adzuki  - I've bought them in natural food stores, Whole Foods and on line  And I buy in bulk so I never run out.  Beans seem to last forever. 