I use a CO2 chamber. There's a DIY thread here on how to set one up. I think mine cost about $30, but I already had the canisters from my paintball daysIt's totally random on how many babies you'll get. I've had some drop litters of 3 or 4, others that have huge litters. If it's staggered, I'd hazard a guess at maybe 30 babies a month? I've never really kept records for my ASF. Maybe I should start lol.