Welcome and ask your questions on the Recumbent and the Alt Bike Culture forums. There are lots of people on the alt bike forum who have cannibalized multiple bikes into stange looking bikes, which is how I think you intend to create a recumbent. Charity shops and garage sales should be a good source of cheap bike parts. Proper spoke tension is the most important thing for heavy riders. You will have to go to the bike shops to buy specialized bike tools. Best of luck