Re: if you were a carrier of one allele for a certain recessive disorder, how c

First, if one is a carrier of a recessive allele, no phenotype (e.g. disease
character) will be expressed from that gene (from that DNA strand) OR the
transcript phenotype of the recessive allele will not have any effect on the 
organism. Second, if one is a carrier of a recessive allele without 
beeing predisposed to the recessive character, the allele is still part of 
is genomic DNA. So if the carrier has a baby with a non-carrier, 
the newborn has 1/2 chances of getting the recessive allele. If the 
carrier as a baby with a carrier for that same character, the 
baby has 1/4 chance of getting the recessive phenotype for that recessive 
character or 1/2 chance of beeing a carrier.

Conclusion: a genetic counselor wouldn`t be able to do much more than to 
tell one 1) what are the chances of you having the recessive allele on 
one or both copies of that gene 2) saying one is carrier or ``affected`` with a 
reccessive allele, what chances that person and their lover has of getting a
baby affected by that character and 3) what are the consequences of a baby with 
a recessive phenotype if there are any. All of this by analysing a 
genealogical tree of one's past relatives (or DNA testing, if it's available for
that character). 

Of course this concept gets more complicated if the recessive allele is 
associated with the sex chromosomes, or the character is only present in one sex
but not the other. The above probabilities apply only if the allele is present
on one of the autosomes and has no sex-specific effect in males or females. 

Please ask again if you still have questions.