I'm migrating from Wink 2 and am having a terrible time. I excluded everything from Wink and shut that hub down.
I started with hardwired Z-wave devices - two switches, one a GE/Jasco and the other a MimoLite. The GE, which is about 10 feet from the hub through a couple walls, paired but the MimoLite didn't. The MimoLite is 10 feet from the GE through a wall. I then moved on to Schlage locks (yes, I have read about issues already). Got them all to pair but they, and the GE switch, don't respond to commands at all. I have 5 Neo door/window sensors that wouldn't pair at all. I then added the Zigbee lights, which are all Sylvania/Osram.
Questions:
1 - I ordered the Aeotec 6 repeaters after reading here about problems with locks and will get them tomorrow. My understanding is that I should place one close to the hub. Should I exclude the Z-wave devices I've already added, pair the repeaters, and then start adding the devices again? They show up in my device list, but when I go to the Z-wave section of the portal, no devices are listed. Two of the locks do show activity in the logs - one a Schlage BE469 and the other an FE599. Another shows six 'null' events. I have repaired and rebooted numerous times.
2 - Two of the Zigbee lights - one is a string of garden lights and the other a bulb - are not updating the status as 'off' unless I hit the tile a second time. In other words, I turn the light on and the tile updates the status. When I turn it off, the lights actually turn off but the tile indicates it is on. When I hit the tile a second time, it changes to indicate off. Should I exclude these and add them again? All other lights update the status with no problem.
3 - Can tiles be added directly to the main dashboard or do I have to set up a sub dashboard for rooms/type of device? There are some things we use frequently - the garage door opener (MimoLite), front door lock, living room lights, and garage lights - that I would like on the main dashboard.
4 - Any tips for setting up a dashboard that will make things easy for the others in my house? One example - I've noticed in my app that I have to scroll from left to right to see all of my devices. I'd like to fix that before I install the app on their phones.
5 - What apps should I have installed? I have not added any yet.
Your first task is getting your devices connected to HE and building strong device networks. I don't know how many and what types of devices you have but until you have "enough" devices connected to provide a strong mesh, devices may not be able to maintain stable communication with the HE hub. I would read the building a solid Zwave mesh and the corresponding Zigbee one as well.
Zigbee and Zwave radios are very low power and walls will absorb most of the radio energy. With enough devices to provide redundat communication paths, your devices will become stable.
If you're otherwise happy with your dashboard, you have a couple options for sizing. If you're viewing your dashboard, you can click the gear icon in the upper right, go to the options link/tab, and check out the "column width" and "row height" options. On some of mine, I have "column width" blank so the tiles will automatically expand/shrink to fit available screen space. You can do this with height, too. But because Hubitat Dashboards, unlike many others, make you specify a fixed number of rows and columns, you might still need to create different different dashboards for different screen sizes (for comparison, if you use a SharpTools.io dashboard, tiles will flow down to the next row when space is exhausted; neither way is inherently better or worse, just a tradeoff between predictable tile locations and tile sizing).
My experience: on my small-screenèd iPhone SE, about 3 wide with automatic width is what I do, and I don't mind scrolling vertically (I have a specified height); I suspect others might be able to fit at least 4 (or more), and you can play around with what works best for you. For comparison, on my 7-inch fire tablet, I'm using 6 columns and 5 rows, all with automatic sizing. Both are still usable on my desktop should I ever want to do so. (Some people also double the number of rows or columns and make all their tiles except certain ones take up twice the normal width and height--a neat trick to making some tiles smaller for things you care less about.) You may have to try a few different things and see what you like.
my 2 cent feedback
1 - It would have been best to wait for the Repeaters but they should slot in ok.
Check what Device drivers have been selected for the devices that your having issues with. Sometimes you’ll need to manually select an appropriate Driver of the auto discovery doesn’t do it.
2 - Not sure on this one.
3 - Sure. Just make more dashboards and link them with a tile called something like “HOME” that links back to your main dashboard. Note you can not restrict dashboard access to some users. It’s all or nothing.
4 - play with sizing as others have suggested.
5 - Get your devices working manually From the Device page before confusing yourself with more options by adding Apps.
One of the many Tile Templates is a Dashboard one. It allows you to have Pages of Dashboards. You can have one Dashboard per floor, one per room, one per function.. like Weather or Swimming Pool
All of them can be accessed via a Dashboard tile. Then on "child pages' have a Dashboard tile to take you back.
You can have 100's of dashboards if you need that don't interlock. Maybe ones specially designed for a specific mobile device that has Dashboard tiles to pages of mobile device sized pages, but not to the Larger ones.
Also.. think about setting up a grid that is 2x or 3x larger. That gives you smaller tiles and then when you size those you can get different shapes. Set a 2x grid.. instead of say a 6x6 grid, use a 12x12 grid or 12x13, then place your device tiles and by making them 3x1 for example, you get a long horizontal tile. 1x3 gives you a tall tile.
Thank you everyone. I am delighted to report that after noodling around for a couple hours I have everything connected. Now on to that dashboard setup...
Apps are basically automation templates on Hubitat--install an app, then choose your devices and other parameters in that app, and you've just automated something. That's how most Hubitat apps work. You can see documentation for most built-in apps 
