How to disable the multivalued in managed schema ?

[Manjunath N S (mans3)]

Hello,

1.I am trying to use the managed schema to index my data. But a  simple single 
valued int,double,float fields are becoming multivalued by default and I am 
unable to sort on them when I make an UI call .(I am reading them as array as 
now) is there a way to make "multivalued=false" for all the fields in the 
managed-schema ?

2.If I choose to use schema.xml,is there a way to add the new fields through an 
api call ?
    I noticed that schema API works only on the managed schema class.

Thanks,
Manjunath