They likely can all do that.
First the easy way is to just turn of the wifi radios in the dsl modem/router. You now have 2 routers in the path but that only causes issues for some game consoles and people that are trying to host servers. Pretty much anyone else will not be impacted by 2 routers in the path. You can even greatly reduce the issues for games by using the DMZ option in the DSL router and pointing it to the second router.
The second way but a little more messy is to put it into bridge mode. You will then need to configure your second router wan port to use PPP. Some ISP you must have a userid and password.
The only way you get good outdoor coverage is to place radios outside. Since you must run power...