Yes, you can use the above tool, but make sure that you use the appropriate Codon bias for GC content and code your gene accordingly. Two organisms with different codon bias/GC content can have quite many differences at the nucleotide level because of degeneracy of the genetic code. Good luck 

Yes, see this online tool:

http://www.bioinformatics.org/sms2/rev_trans.html

Yes, you can use the above tool, but make sure that you use the appropriate Codon bias for GC content and code your gene accordingly. Two organisms with different codon bias/GC content can have quite many differences at the nucleotide level because of degeneracy of the genetic code. Good luck 

Hello,

I think there would be various tools available online. I am currently using CLC genomics workbench for something else but it does have an option to reverse translate protein sequence. You can try their 14 day trial.

Hope this is of any help.