The POIs that are on the right hand side search menu in Basecamp show up on the BC map if the approprate level of details is shown.
They are not included in any GPX file that is sent to the Zumo unless you select one and make it into a waypoint.
Apparently - accoridng to the on-line Basecamp manual, if you have created POIs and sent them to the Zumo using (say)POI loader, then Basecamp can read those Points of Interest and plot them on the map.
I have read on these forum pages, that people have used BC to create such points of interest. My offering regarding such things are in this
link here.
It is worth noting that although BC puts the heading Point of Interest at the top of the right hand column after intitiating a search, I don't believe that what is presented to be the same as what POI loader creates as Points of Interest.
I have not seen any way of adding the type of POI that I describe (from garmin's documentation) to the Tread App. Not have I found any way of loading tracks into the tread app to enable it to synch. (But I haven't looked particualrly hard).
The XT2 has its own POI database. the Trip Advisor database, the Michelin Green Guide - which allow you to search a particular location and display them on a map on the Zumo screen. There are also categories - which allow you to search for similar things - but the link simply takes you to the Garmin Explore download page.
In Settings->Map Display->Map Layers->Up Ahead places You can select a number of different categories that show on the map ahead, and can also be displayed in a small window in the right hand side of the screen. (I have my own categories in there which are searches for XXX yyy ZZZ - because most of the time, I don't want them cluttering up the display - but I do want my waypoints to be displayed.
That isn't an option, but waypoints only show if Up ahead places is turned on. edited - it seems that was true for the XT1, not true for the XT2 On the map display, you have to select the 3 bar menu and choose -"Up ahead" You can then select one of these to obtain an animated list - showing a direction arrow and a distance. List is ordered - nearest first. The map button shows a map with all of the nearby locations plotted. You can zoom in on the map and delect one of the points and details are shown at the bottom of the screen. Tap that button at the bottom and a new page opens with a detaial map, and POI details. (with price info if it is a petrol station).
If you are just referring to waypoints - with an icon saved in the XT2 - they will appear on the map, but - (it is a while since I checked this out) - the map layers->up ahead places needs to be ticked - which is why I use the xxx yyy zzz searches - because I want to see the waypoint symbol but not every petrol station, cashpoint machine and restaurant. in the vicinity - they clutter up the map.
Oh - the XT2 has an option to trim out display of waypoints to stop it them cluttering the map at certain zoom levels. I've not tried it out yet.
I've probably missed some stuff - but something in there might be what you want. I'll see if I can get a screen shot of some snippets showing icons and add it to this post.