I’ve toyed with these ideas. The only reliable way to do this is as follows;
-Get a conventional alarm system. DSC is the best for Vera integration.
-Wired security grade contacts, or DSC wireless contacts work much better than consumer level Z-Wave stuff. Should be cheaper, too.
-Envisalink 3DS is an after market 2 in one DSC module. It does IP alarm transmission to a monitoring company if you so choose. Also, it will handle Vera integration.
-Proper scenes set up in Vera, to allow arming and disarming of the alarm in it’s multiple modes.
-An always on Tablet, with the security set to always require a a code / pattern or something to get into it. Widgets using Tasker or Home Buddy on the main screen to allow easy access to turn off the alarm during entry delay. There ought to be more viable ways of having the Alarm trigger the Vera, and the Vera triggering action on the Android. Tasker is the main app to look into, and then look at AutoVera plugin for Tasker. It’s beta, and brand new, but may allow some interesting ways of getting the Android to react. I am fairly confident that the only “Keypad” style app that exists for Android is one called “DSC Security Keypad” The problem with it though, is it uses the same API to talk to the Envisalink and DSC system that the Vera would. As such, you can not use this app in conjunction with a Vera, currently.
Be careful here!! An Android tablet can only be made reliable enough as a secondary security interface if you lock it down. Don’t allow lots of apps on it. Use it sparingly. Tablets have Lithium Ion batteries in them, but if they are never discharged, I can’t comment on whether or not they will be any good after years of non-use. The better way to do this is to snip the AC adapter cord, splice a wire, and fish it within the wall to the basement and power it down there. Also, don’t go stupid cheap on the tablet either. You will want something that can run the full gamut of Tasker implementation. Hence the newest Jelly Bean, baby! I’d suggest the Nexus7 because it will always be up to date.
-A real alarm keypad nearby. You can hide the ugly thing in a closet or something, as your tablet is so much nicer. Do have it nearby though! Don’t rely on an Android as a keypad during entry delay or an alarm situation. Always have the real security keypad available as a backup in case the tablet is having a nap or a temper tantrum. Remember that security vs consumer grade considerations actually matter when it comes to reliability.
-A UPS is advisable. Battery backup for your Modem, Router, Vera, and your Android power adapter. Not only does it provide surge protection on the power, but if you get a good one, you can protect the coaxial or phones in, to avoid sideways surges. If you use the Envisalink for monitoring through Eyez-On or another professional company, the UPS will keep the link going during short term power outages. This will keep the whole Rube Goldberg machine working well.