Thanks for this question. It brings to the forefront a common question among hospitals looking at mobile solutions. It is most important to state, that what is the BEST DEVICE and what things concern you, could be vastly different.
The best device could be based upon platforms (for example a fully integrated McKesson hospital with EHR, PACS, EMAR, etc.), and what solutions they offer. It could be based upon budgets, GPO vendors, etc. However, the most crucial criteria, in my opinion, is the physician acceptance based on their current devices, needs, and wants. The link below is a recent article confirming this, and directly relates to your questions and concerns, based on research!
For the things that concern you, they are valid concerns also addressed in the article. For example, your concern of ease of use in the research states:
"Physicians just really love the ease of use of the <apple iPad]," said Meredith Ressi, president of Manhattan Research. "It's intuitive, and they know it's not going to give them a bunch of technology headaches." Thirty percent of doctors are using iPads to access electronic medical records, view radiology images and communicate with patients, according to Manhattan. An additional 28% of doctors plan to buy an iPad within the next six months."
Again, great question and below is the research/article that addresses it.