They should never be the sole criterion for picking a fund, but they should figure in along with risk, expenses, past performance and the suitability of the fund category to your needs.
Setting up an LLC protects you from personal liability. (If angry creditors come calling, or if a customer slips in your store, the lawyers can't go after your house.) Unlike with sole proprietorships and partnerships, only the amount of money you put into an LLC is at risk.