It is illegal for anyone including an attorney to charge for filling out an application, so better that you take the task on using the resources that are contained on the site and this forum.
We would suggest that you print off all the forms on the site, follow the step-by-step directions http://www.vetassist.org/forms/Step%20By%20Step%20Guide%20FINAL.doc
Use this format from the forum http://veteranaid.org/forums/index.php/topic,264.0.html
If you are not sure as to what to deduct for medical expenses use this as a guideline on how to arrive at his countable income.http://www.vetassist.org/eligibility.htm
If you run into a stumbbling block, do a search on the forums for the topic, if you don't find the answer, post a question.
Be sure to keep a copy of the entire application for yourself and always send everything
Registered Return Recipt
Use form 21-22a
making yourself the Claimant's Representative.
If your dad has any mental issues that the VA would find him to be unable to manage his own affairs, you will have to deal with the fiduciary process after a decision has been made on the applicaiton.
The processing center that handles applications for Arkansas is
Milwaukee Pension maintenance Center
5400 West National Avenue
Milwaukee, WI 53214