You can operate your business as a business unit under the corporation through a DBA. There is nothing stopping you from doing that. You might want to check your insurance policy to make sure you are covered but there are no business form issues that I'm aware of that would stop you from doing th...
Can you describe the data in the table? I can think of a few solutions, most if which are based on the data you are storing. For example, chances are when you have large tables you are probably not doing any summarization of your data. If possible pre-compute the result and spit out the answer ...