You should keep your hummer feeders in shade regardless of what type of food you use, though, as it will turn fairly quickly in direct light and hot temps. Hummers like tubular flowers, or anything red, but will come to almost any colored flower if hungry. Also, after a time, they will become accustomed to your presence and you can get fairly close to their feeders without alarming them. This makes those window feeders a great choice, especially if you have children. As for snakes, I don't know of many that are attracted to flowers.
Most snakes eat bugs or rodents.
Re snakes - since they like to sun on a warm patio, I would expect that shade from plants would discourage rather than encourage them. I live in Missouri and have had my first Humming bird just this afternoon. I have had my feeder out for about a week and this is the first time I noticed them this year. AS for the snakes if the patio is of a stone floor or somethinf that will hold the heat the snakes will be drawn to the heat as long as it is chilly. You don't say what zone you are in but here in California, the Anna hummers don't migrate.