Your mortgage company should send you a release of lien, and it must be filed with the County Clerk 214-653-7275.
Small claims are cases filed in the county justice of the peace courts (also referred to simply as "justice courts") in Texas. Justice courts provide a more informal setting than the higher-level courts, so parties will often represent themselves rather than hiring an attorney.
No. You are not required to hire a lawyer to file a Small Estate Affidavit in Texas. Many probate courts offer downloadable forms and clear instructions for filing. For example, Harris County provides a very good small estate affidavit form (pdf), as well as detailed instructions for filling it out.