Compost piles do need to get hot before the seeds and weeds are destroyed. The best formula I have found is 1" animal manure, 2" green manure. To be safe, make two piles. Start them 6-10 months apart. Let them rot for a year and turn often to aerate. Yes, you can use half rotted compost but only in the vegetable garden. Works really well if you dig a trench and bury it or for squash and cucumbers, dig a hole and bury it. Don't top dress with unfinished compost. You will get all kinds of volunteers in with your flowers.