I'll answer your original question in detail here:
BASIC CALENDAR "OVERLAY" NEED
Talking about single person calendars.
Yet multi sub-categories, like this:
Internet-Radio-TV
Christian Conferences
Financial
Auto
Business
Local Events
Input through Windows mostly.
-Steven Avery
If you are going to input through windows, i highly recommend inputting directly through outlook. Full paid-for outlook on windows desktop. Why? things like recurrence work better on outlook (especially something that has no end date). Outlook can do multiple calendars, and multiple categories...both will allow you to color it independently. What's the difference? Not much, really. Depends if you want one calendar, multiple categories....or multiple calendars, one category. I suggest multiple calendars, forget categories...why? because the colors you choose for the categories will not transfer to different apps (like android or ios), but you will usually be able to custom color each individual calendar. also, you dont have to worry to choose a category when entering a task...just pick the calendar you want.
EXTRAS
Possible +, not fundamental
shows on iPad (ok, Android too)
groups of people, good for BIZ - (Zoho has that)
integration with email, task, notes etc. (not that important for me, since I am Rightnote and Eudora/TheBat! oriented)
A calendar entry is quick enough to enter. the 3-second saving from a Gmail is not important, since you always tweak them anyway.
-Steven Avery
any outlook calendar will show up on ipad or android or mobile.
contacts management is a different issue and headache altogether. i can post more later, and i also have several good posts here over the years regarding contacts.
integration...i use the bat also. and rightnote (although i have now moved to onenote almost exclusively). for contacts, i have my own cardav server....the bat cannot sync with it, it has issues. i dont think the bat has good contact/calendar syncing features. it doesnt even have a real calendar.
rightnote has good features, but difficult to make part of this workflow. you must be doing something very specific.
your OVERLAY requirement...
If what you mean is multiple categories/calendars showing on one display with different colors etc., I'd stick to outlook. Use multiple calendars.
ultimately...i would get something like calendarscope or other 3rd party software (like i used to), but only outlook's features are reliable for me, so i use it alone now, and just apps on phones. I VIEW my tasks on outlook on the pc, and on Digical on the phone. Alarms would be something you setup on the phone and should be independent of the app. Outlook or most calendar apps dont have specific ALARM functions....if that's important you probably want yet another 3rd-party pc software or app to do that. That should be fairly easy to find I think.
I'd stay away from committing to suites like EssentialPIM or something. Think about syncing. Facebook events are terrible and will have many many problems syncing with things. It's all been a frustrating experience for something so common, old....i've been doing this for so long. For years, the big three google apple facebook kept fighting and pulling their sync tools away from each other and now none work all that well unless you pay for extra services.
there is one tool i am looking into committing too once again, Mylifeorganized. It has a nice workflow and can do a lot. Not really a true calendar software as it has no calendar view, but has some very interesting features to organizing tasks and integrations.