1. as above
2. I did a separate PGY1 at another hospital and now doing a PGY2 for another health system (or more accurately I'm still within the same health system but at a different "sister" hospital) - difference would be that you would be more comfortable and familiar with the hospital had you already gone through that first year there - I would say it helps from that sense when I speak with my other HSPA PGY-2 brethren about this.
3. My PGY-2 has a required IM rotation and you can have another elective to be something clinical too. In addition my staffing weekends include the Friday so I can have more patient contact time. It is definitely much less than my PGY1 but electives aside and all the other fluff that happens during PGY-1 I wouldn't say its much less in my case. Then again that's only pertinent to my experience. Your going through HSPA because your ultimate career goal will most likely not have a focus in patient care. That being said I have a handful of friends who went through a PGY-2 in HSPA and then worked as a clinical staff pharmacist after for a year or two to brush up on clinical stuff before heading into the real deal admin-y jobs.
4. As above - also showing an interest in what HSPA is and being able to have a tangible career goal helps (manager, director, coordinator) etc.