So I want to wire in a oil temp and oil pressure gauge both are VDO. To run the wires from the engine and hook up power to the gauges I would like to disconnect the battery so I do not fry any wires. Will doing that cause any issues with my restarting the car? Will I lose the mileage on my dash, this is my first car with a liquid Chrystal odometers. Silly question but it will be disconnected all weekend, since I figure this is a two day job to do it right.

 

No problem, depending on the radio you have it may lose the station settings.
The clock will need to be reset.