If you remove the batteries, the Super UFO will still work. SRAM and DRAM will function normally while the Super UFO is running in the SNES. After the power is shut off though, all data in SRAM and DRAM will be lost. If you backup your SRAM, this isn't a big deal.
If you wish to have the batteries replaced but cannot do it yourself, I suggest Asking Ulasamosa, if you're in the USA. But... Going by your English, it's possible you're located somewhere else.
If Wolfenstein 3D does not use a co-processor, then it will work. I've never heard of anything like that so presumably it is a basic HiROM or LoROM game.
In case you don't know, HiROM and LoROM refer to addressing, it's complicated, but they represent the basic, simplest form of SNES game. Super Mario World is a LoROM game for instance. A lot of SNES games are either HiROM or LoROM without co-processors, so the Super UFO is still very compatible.