Colonel,
There are several option to "aquire" land to build on. If you want to rent it out it would rule out "Hak Pakai", so you should lease or buy with the nameholder option, see this page:
http://www.bali-information.com/bali_pr ... e.php?p=11
Building a villa will cost you depending on quality and material somewhere between 1.5 million and 5 million rupiah per sqm, where 2 million is a reasonable average. But I am talking VILLA here and not house.
Time frames? Her in the north we can build villas within 3-4 months, somewhere else it may take twice or more.
Don't forget, depending on location, to calculate making roads, getting electricity and water, and making the land building ready.
For one spot here in the north we used more then 2300 truckloads of soil to get things done. But that was for about 2 hectare of beach land. (5 acre)....