basemapcartoqgis
I am trying to add a CartoDB basemap to QGIS and am 1) trying to figure out if it is possible and 2) trying to figure out how to do it.
I've installed the QGIS CartoDB plug-in and have connected to my account. When I select Add CartoDB layer from Web >> CartoDB Plugin >> Add CartoDB Layer I only see the data layers I've uploaded to CartoDB, not any base maps. How can I access the basemaps?
Even after installing QuickMapServices I do not see that CartoDB base map: 
You should load both sublayers through createLayer, then turn off the one you want to hide initially.
The following works if you have two tables in the visualization you created in CartoDB Editor. If you want to add layers without having a viz.json link, you can create the layers at runtime.
// Instantiate map
var map = L.map('map', {
center: [39.8282,-98.5795],
zoom: 4
});
// basemap url
var mapURL = 'https://cartodb-basemaps-{s}.global.ssl.fastly.net/light_nolabels/{z}/{x}/{y}.png'
// add basemap tiles to map
L.tileLayer(mapURL, {
attribution: '© <a href="http://www.openstreetmap.org/copyright">OpenStreetMap</a> contributors, © <a href="http://cartodb.com/attributions">CartoDB</a>'
}).addTo(map);
// add cartodb data layers to map
cartodb.createLayer(
map,
'https://jonmrich.cartodb.com/api/v2/viz/50366df6-afed-11e4-ab33-0e853d047bba/viz.json',
{
https: true,
legends: true,
cartodb_logo:false,
layerIndex:1
})
.addTo(map)
.done(function(layer) { // when successful, do this stuff
var sublayer0 = layer.getSubLayer(0);
var sublayer1 = layer.getSubLayer(1);
// hide sublayer1
sublayer1.hide();
$("#load_3").on('click', function() {
// turn on layer off, turn off layer on
sublayer0.toggle();
sublayer1.toggle();
});
})
.error(function(err) { // when error, do this
console.log("error: " + err);
});
Your points disappeared because you not specify Spatial Reference at last step adding csv to the map.
Your csv data are in WGS84 and base map (i.e. Google or Bing is in Web Mercator). Also you need to enable reproject on the fly.
Best Answer
Have you tried QuickMapServices plugin? http://plugins.qgis.org/plugins/quick_map_services/
Settings → More Services → Get contributed pack