A lake of your size is much tougher to manage, that is for sure. A lot of your questions, the answers to them is "it depends". The adding of genetic diversity certainly cannot hurt! However, if you add 1000 2.5" to 3" LMB fingerlings, how many of them will survive? Much of it depends on the quality of your forage base in your lake, the population structure of your bass and other predatory fish, what habitat is available to fingerling bass in your lake.

That fact that you are culling is good , it should help keep your bass population in check. You may want to pick up the culling the bit if you plan on adding more bass. If you have access to a smaller pond, you want to consider growing out those smaller bass until they reach the 8" to 10" mark and then release them into your larger lake.

Best of luck!