Your questions are all without or with little context and as a result hardly to answer. It seems to me that you want us to do your work: reading the documentation and available documents. You should do this FIRST and ask more specific questions afterwards. If you do want somebody else to do your job then - as Ronald (kukeltje) already mentioned - you have to hire and pay somebody!
1) There is an API for the process engine. You should read the manual about that.
2) From within a process I think there are ways to do it. You did not give any context. Read about the API to access the process engines and about Java Tasks.