Size will be more than enough. The tank size only regulates how often the motor kicks in. A wide format press is unlikely to be closed three or four times a minute (unlike a garment press), so the motor won't be constantly running (duty cycle), which in turn wil make it low use. Most compressors come with a duty cycle of 50%, which means the motor should only be running for 30 mins per hour.
Oil shouldn't be a problem on a day to day basis when in use, but you are supposed to open the vent valve periodicaly to release the build up of condensation in the tank. This might have some oil in it.
Bambi compressors are 'super silent' and run at about 40db, so they can be used facing the customers. Most compressors run at 95db and need to be in another room or in a sound proof box.
There are some 'halfway house' silent compressors that run at 60 db, which is comfortable enough to work alongside with out ear protection, at about half the price of the Bambi range.
https://www.toolstation.com/scheppach-h ... sor/p97037