[HayZee518]

most utilities won't let you put a new meter in the basement of a dwelling [single family or even a duplex] the new meter HAS to go outside. multiple metering is only for apartment complexes and even these are installed outside. ok the existing service is in conduit?? don't get your hopes up that the se conductors will handle 100 amp. a 60 amp existing service used #6 solid conductors. you'll need to install an aux ground rod, water pipe ground and clamps around the meter just like your other installation. the existing entrance pipe is probably a 1 inch rigid conduit. for a sub panel you'll need a two pole 60 feeding a 6-4 cable. neutral is above ground and the equipment ground goes to an auxillary ground bar. I hope you are not getting in over your head.