Where can I send this letter to for uscis?

Send the letter to the address on the I-130 receipt ... include the receipt number.

Should I contact embassy and offer more information?

Sure, you can send them an e-mail ... but, it is a minor error and shouldn't impact on your case. Rather, many, many people are put into...

I have applied for OPT AND IF USCIS asks for an RFE HOW DOES IT DO?

I'm confused. What does "an i20 with opt recommendation is missing on my end" mean? Does it mean that you sent an I-20 w/o the OPT endorsement?

How can I go about bringing my dad back to the U.S ?

Was he ordered deported by an immigration judge? Did he have a lawyer help him? I ask because he might have qualified for cancellation of...

I have re-classified this as criminal.

Am I allowed to apply for the E-2 from the US while on a B-1 business visa?

Yes, if you wait 90 days, you can file for a change-of-status without leaving the US.

While an employment-based green card application is pending, does the individual maintain legal status in the US?

They remain legal if they have filed form I-485 and I-131.

I don't know if I'd use the word 'easy' nor 'easliy' ... put it is possible .... depending on the reason for your deportation.

Yes, you can attempt to enter the US. If you have a departing ticket a SHORT number of days after you request entry... they might let you in. ...

How can I get my dual citizenship US/Honduras?

You need to talk to someone in the Honduran Embassy in Washington, DC