We quit farrowing  about 8 years ago.   I ran the farrowing house.   1.  Farrow on raised floors, to  prevents scours.   Visit a pork conference trade show.   or the Pork Expo to see the different farrowing setups.   Talk to any purebred guys at the fairs to see what they use for facilities.    2. Depending on  location...  what months are you farrowing?     There is an art to farrowing in :   July and August in the heat.   And December - Feb  can be tough too.     3.  Make certain you have a market for them.   And that you have a place to slaughter them.   I agree with others  DO NOT  slaughter and raise pigs in the same place.   

Finish them anyway you want.   Just make certain you can deal with the manure.  Don't let it wash  down the hill.   Be aware that keeping all ages of hogs close to each other can get nasty.   If the finishing pigs get sick,  that younger pigs and even sows can easily catch it too.