This is an option that I was considering, do you think this can be laid fair and square or would the firms back up and say they 'did not expect' this much demands? if you still recommend it, Mr. Donaldson, can you recommend me a firm in Houston that does that? Many thanks in advance.

It's hard to say whether you would have issues with a firm working more than it anticipated, however, the agreement should quote fees and costs up front so you don't have to worry about such an issue. You could also split the work into milestones with a separate quote at each stage. Sorry I don't know of any firms in your area at this time.