Doomie, I apologise for not catching on quicker that you're self-publishing. When I saw your question to me, I didn't read the rest of that post. Doh!
That being the case, you really need to put any thoughts of a Spanish edition on the back burner for now. Self-publishing and then selling your book is a double-time job, in addition to any regular job you might have. Any time you expend right now on a Spanish edition will be time NOT spent on the English one.
In these circumstances, I'd suggest that you not think about the Spanish edition until you see how well the English one does. If you pay off your investment reasonably quickly, then you could start putting some of the proceeds aside to create a Spanish edition. At that point, start up a search for an experienced literature translator, someone who translates books such as yours. Find out how much it will cost, and budget for it.
Remember that as a self-publisher, you have to do a lot more than just write the text of the book, and while some of the things you learn (such as how to negotiate a good printing contract) will carry over, many others will not (if you're not fluent in Spanish). Just as you need to hire an editor for your English text, you'll need to hire one for the Spanish. (Writing and editing aren't skills that are very often possessed by the same person.) There's also cover, back blurb, front matter, and back matter that you'll have to have someone write and then edit (or at least proofread). If your book has an index, it'll have to be re-indexed in Spanish. There will be marketing and promotional materials to be written in Spanish.
You're already starting out on the tough road by self-publishing; don't make it any harder on yourself by trying to do both English and Spanish at the same time. If your English book does well, then look into Spanish. That way, you have some hope of staying sane -- or, well, as sane as any of us completely mad writers are!