Hi, Sherry: Allow me to make a couple of observations, I hope they don't confuse or mislead. The film you cite, LGM306, Reel 26 [LDS #1782812] is only an index which I SUSPECT was either prepared at the time the books were microfilmed or perhaps even earlier. An "index only" will not contain actual documents but only assist one in locating actual document images elsewhere. The index card you cite, "Inventory & Appraisments Filed, Nov. 8 1853, M. C. Lane, Judge, Minutes of Court 1853-1857, page 148", is telling you where the document may be found. In this case, I believe you need to go to the film group listed below:
The corresponding LDS film numbers are 1769657 and 1769658. So when you say that "there is nothing pertaining to estate records for the time period 1853 to 1854" - it just isn't so. If you go to the Tallapoosa County GenWeb site, you will find numerous estate documents which contributors have transcribed and posted. Some do involve estate matters for the period in question and they cite the microfilms I have listed but using the LDS numbers. I think that the film collections (LDS and AA&H)are one-and-the-same, only AA&H has assigned their own numbers to them - I see that all the time. At least a couple of postings involve matters heard by Judge M. C. Lane, one in February 1853 and another in the following month. I didn't look at all of the transcriptions so there might be more.
Furthermore, if you haven't been to the GenWeb site then you might want to take a look at it. There are many good local sources listed with contact info. Particularly note that there is a fellow who conducts research in Tallapoosa County, including court records. If he is still kicking, you might want to call him - if he is worth his salt then he should certainly be able to tell you whether or not the county records have been microfilmed. I'm convinced that the bulk of the records are on microfilm although it's possible a few things might have been overlooked. If you need a link to the GenWeb site, just ask.
I hope I haven't muddied the waters but I too have ancestors from the area and may be doing some additional research so I'm very interested in what you discover - please keep me updated.Rick
PS - courthouse personnel can often be very helpful but at other times totally disinterested and quick to give researchers the "bums rush".