"Go to Today" is grayed out if "Today" is already visible on the gantt chart. If you scroll away so that "Today" isn't visible then it should work.
MS Project files that are imported into OmniPlan will show up as "Untitled". It's only after you save it as an OmniPlan file that the title shows up.
If it's not working as I described, please send us an email at
omniplan@omnigroup.com. Thanks!