Here is a short article that helps with some of the process modeling questions you have.  Technically the answer may depend on the precise standard you are trying to follow (BPMN, UML, etc). But practically it really doesn't matter.

https://www.modernanalyst.com/Careers/InterviewQuestions/tabid/128/ID/2729/Can-you-have-multiple-start-and-end-events-in-BPMN.aspx

A few things of note:

1. BPMN processes can have multiple unique start points.
2. Two starts that have the same "trigger" are actually the same start.  The trigger is always satisfied by some set of preconditions.  So, think about what those preconditions should be.
3. If you find yourself starting a process with a decision then you probably have some task or activity before that decision. Or, the decision is two starts with two separate triggers that go into two flows.

I think with this information you should be able to figure out the answers you need for your specific cases.

As for 2 stakeholders; you could consider combining them into a single stakeholder. A stakeholder is a role, like project manager of program manger. 2 roles could be combined into generic role, like IT manger. This saves duplicating functionality that is performed by both roles.