LLC Profit Distributions

I set up an LLC with 6 other people, and we all have unequal contributions. For the profit distribution, we were going divide it between the members based off the capital contributions, but then a huge problem came up. Their was a major in balance of work being done. Those with the most interest are doing the least amount of work, but are getting a significantly higher percentage of the money. I did research, and they said that you can set up your operating agreement to account for inactive members, and I was wondering, Can we change our percentages every year, based on the work done by each member done, and do this right before the taxes are due, so that people do not lose their incentive to work? Do the percentages have to be set in stone? Is their another way to pay the members of a LLC without having to do it via percentages?

Another somewhat related question is does all the money your company makes have to be paid out to the members at the end of the year, so it can be taxed, or can it go into a company fund, like a reserve fund, without it needing to be taxed first, or run through the members taxes?