When you load the menu option, the values you see displayed will be the values currently in use by your game. Vanilla values are 3.3 and 2.0. If the menu is displaying different values, then you have a mod installed which is already adjusting these two settings. If you choose to select a new setting, Trade & Barter will override the settings from the other mod. If at any time you wish to revert the settings back to those made by another mod, simply deselect this setting and reload your game. You will need to reload your game before the changes from Trade & Barter are fully canceled out.
I have made every attempt to keep this mod as compatible as possible with all other mods, and it should be fully compatible with nearly every mod out there. There are a few features that may conflict, but these can be toggled off to maintain compatibility. The features will work just fine with merchants added by other mods (assuming they've been placed in the proper factions). In fact, while this mod does work very well on it's own, my primary intention was to create a mod that would compliment and enhance existing mods that already overhaul Skyrim's economy.
A place to exchange your books with other members, Bookins says that they have “more available books than the largest Barnes & Noble.” Best of all, there are no membership charges or fees to speak of. Bookins arranges all the trades for its users, so members never have to contact each other at all to set up swaps. Sending items is free of charge, while receiving an item costs $4.49.
There are several disadvantages of the barter economy. Firstly, there has to be double coincidence of wants for exchange to take place. Again the problem of indivisibility of commodities comes in the matter of exchange. Basically such disadvantages and many more called for the emergence of money. Money is used as a common medium of exchange and store of value.
As Orlove noted, barter may occur in commercial economies, usually during periods of monetary crisis. During such a crisis, currency may be in short supply, or highly devalued through hyperinflation. In such cases, money ceases to be the universal medium of exchange or standard of value. Money may be in such short supply that it becomes an item of barter itself rather than the means of exchange. Barter may also occur when people cannot afford to keep money (as when hyperinflation quickly devalues it).