Advice on Restaurant Ownership... It's going to be tough, long, and either the wife or friends won't be a wife or friend by the end.
Consider the future, you or someone will bow out. Accountants and/or Lawyers will be involved and they don't know GnuAnything. They know QuickBooks.
You may sell your restaurant as a group, the buyer will likely want to see the accounts in QuickBooks.
You may be successful! congrats! you can now hire an accountant, they'll want QuickBooks.
In short, pool the wife & friend's money, pay the minor entry-fee for QuickBooks and save yourself the time (which you'll need the most now).