Milz

They are the same. When entering the A# for things on the USCIS site(such as e-verify and paying ELIS fee), they state if that it is less then 9 digits, then insert the 0 at the beginning after the A.

Ecuador has a reputation on this site for being a difficult country for K-1 visas. Do yourself a favor and search for some threads in the appropriate regional forum and also read the consulate reviews.
Your case might receive further scrutiny because you are second cousins not because marrying your second cousin is illegal, but because of the possibility that you're simply doing a family member a favor instead of truly being in love. Be prepared to prove that your romantic relationship is a legitimate one.
With income below the poverty line, you'll need a co-sponsor. Again, check to make sure the Ecuador consulates allow these, as some consulates do not.
If your girlfriend (fiancée if you're applying for K-1, by the way) is only 20, chances are she has weak ties to her home country, which would make a B-2 visa difficult. But I guess it's worth a try if you don't go the K-1 route.

The age gap won't be a problem at all, because it's common in Ecu for younger women to marry older men.
The consular regime has changed, but when my contemporaries and I were going through the hellhole Guayaquil consulate, the subject of finances never came up. That might have been because everyone was qualified, and you admittedly are not. I presume that if you have a cosponsor, the financial aspect won't be an issue.
The family relationship might raise some eyebrows, beyond the consulate's historical focus on the bona fide nature of relationships.
In your eventual I-129F petition package to USCIS, I would recommend including a very carefully composed letter, addressed to "Immigrant Visa Consul, U.S. Consulate - Guayaquil." Include in it your relationship timeline, starting with all contacts (presumably incidental) with your cousin before you decided to date her. Focus on the "unexpected" (your term) start of your dating. Then, give the date-ranges and highlights of your various visits. Include language to the effect of "after the third visit [or whenever] and a total of ___ days spent together, it became clear that we were compatible and mutually committed enough to consider filing the I-129F petition and applying for the K-1 visa." Include objective language that would convince a third party (the consul) of the bona fide nature of your relationship, and concentrate on the number of visits and amount of "face time" spent together. Close the letter by saying (in bold type, as here) "We will have much more evidence of our bona fide relationship to present at the K-1 visa interview."
If (and only if) it's true, include in the letter a statement of concern that she will be drastically homesick at having to leave her family.
Have phone and Skype records (summaries, with key printouts of communications over the course of your relationship that you want seen). Save every photo that you've taken together so far, and take oodles more on your next visits.
I strongly recommend that you wait until mid-2015 to file the I-129F petition. In the meantime, visit her at least twice more and spend as long a time together as each visit allows. A good 1.5 years with multiple, quality visits will indicate the enduring, bona fide nature of your relationship.
Most important of all: You must absolutely be there with her when she goes for her visa interview.
Take the maximal time possible to conceive, compose, and massage the text of the above letter. A period of weeks or months will yield the best logic and details to include.