vanityfair

To be completely honest, this sounds like a fair number of red flags (though I don't know how significant age difference couples are treated in the Dominican Republic culture, but the language barrier will definitely be your greatest obstacle. Not to mention, knowing each other for only 6 doesn't help either). I'd highly recommend front loading and visiting a few more times with a fair number of photographs with her family and friends. Also maybe start collecting evidence of efforts made by one or both parties in learning each other's language (it couldn't hurt).
Actually, when it comes to language barriers, this case comes to mind:
http://www.visajourney.com/forums/topic/576753-interview-today-visa-refused/page-1
You should definitely be prepared and preemptively cover as many red flags as possible (relationship length, face time, and language issues will probably need to be covered).

Yes, you will need a co-sponsor for this who makes more than $19,912 a year based on their tax records (or more based on how many individuals are listed as dependencies on their 1040 tax return). So you and your cosponsor will both need to fill out an i-134 eventually with tax reports as supporting evidence (either a tax summary or a 1040+w2s for the past year). Even if you don't meet the poverty level, you still are required to submit an i-134 with supporting documentation as the petitioner. If you don't find a cosponsor you probably will be denied at the interview level and asked to return with a cosponsor.
Unless you have a substantial reason for not filing taxes, I would use the time now (while preparing your documents to submit with the i-129f and waiting for it to be processed) to file your taxes at least for 2015.

Yeah the USCIS, NVC, and embassy will not look at any digital content. You will need to print out the documents and send it to them (I presume you got an RFE?).
However, you probably don't need to send all of it. Just pick snippits here and there and organize it on a word document before printing it out. Having all of it sent might be overkill.
No, it isn't going to ruin your chances of getting approved as long as you give them what they ask for (AGAIN presuming that you got an RFE from this.) I wouldn't worry too much about it.

This is what interests me as I wonder what they mean as facetime as it is fairly vague for me. For example, I wonder if they look into how many hours/days one spent together consecutively as I have yet to spend a solid straight week with my fiance, but I have been seeing him every other weekend for a casual date and meal for the past few months (not to mention knowing him for about a year and a half so far and me thus meeting him for over a dozen times in person).
It is certainly nervewracking as I have no idea how the embassy is going to interprete this.