Hi Shane,
1 and 2 are unrelated.
1. Please go to SE80->BSP application->/persos/mainapp". Under that "MIMEs" folder.
You will notice that ScreenMode.js has been renamed to ScreenMode.js.BAK OR ScreenMode.js.BAK1.
Correct the extra BAK or BAK1.
for slightly more info, please see Personas: ScreenMode.js?
2. This is happening because the tab caching is failing. Can you please check whether the transaction you are trying requires overwrite entry or not :
1999747 - SAP Screen Personas Screen ID and Control ID overwrite rules
IF your transaction is note listed in above note, please report it.
Regards,
Sushant