I'll speak to what I have knowledge on:
Yes, you should be able to configure this easy enough with rule manager. It really all just depends on which apps you want to how on how you would accomplish it. Lots of options here.
I use a Raspberry PI running VLC Things plugged into my all house speaks and it works great. You'll need a custom driver for it [statusbits : VLC Thing] - Porting VLCthing - #12 by cwwilson08. Very easy setup.
Your limited to 10 SMS a day if you go this route. I'd recommend PushOver app as a bridge until they have their own app. Basically you install the build-in pushover driver and the pushover app, create an account with pushover and grab a key and throw them 5 bucks (after a 7 day trial) and your good to go. You can do 7500 push notifications a month and configure custom sounds and rules also.
You'll need a custom app for this [smartthings : Logitech Harmony (Connect)] -Harmony Hub Integration - #18 by mattw and a bit of borrowing from smartthings in terms of an API key. It works well for our needs.
Personal opinion here, having come from WebCore... No. You can install WebCore on Hubitat, but I found it to be slow. I've started just making custom apps and modify existing ones via groovy. Its not a big stretch from WebCore (but I write code for a living so that might play into it).
I've been using it for about 2 months now with no service interruption (aside from those I cause messing around ) Dropped smarthings and never looked back.
We're an Lowes IRIS house hold. I have about 47 devices - keypads, contact, motion, and temperature.
I used ActionTiles on the previous system, so I found the build-in dashboard to be limiting from what I was use to BUT they are working on it each update. I ended up deciding on Sharptools.io, which Hubitat partners with. Note it is a cloud based solution (even at home) but works great otherwise.