Timber products should never be placed in the dishwasher or soaked.
If your board/utensil is left in the sink for extended periods of time the boards will warp and potentially split.
To remove those dreaded meat and veg stains put some lemon juice on and rub some rock salt against the wood to clean. This will remove stains and any odours.
From time to time is advisable to treat your boards or utensils with a light coating of mineral oil. Periodically a light sanding will bring your board/utensil back to its original finish.
In regards to the toast tongs, simply dip the ends in warm soapy water and allow to dry naturally.
In regards to boards, both sides of the board can be used for food preparation. There is no cross-contamination between wooden boards so long as they are cleaned and dried properly.