That's pretty much it. Remember, with these new fangled machines called computers large numbers of calculations are a breeze! no seriously, for a space invaders type game checking the player against all other enemies and checking each bullet against all enemies should give you no performance issues at all. When you do get into bigger scopes then to optimize your collision checks you gotta get into some kinda spatial partitioning tree like BSP trees, quad trees and the like. But even those are still doing all the same checks, its just the tree structures usually make it so the top couple levels are all the entities closest to the object you're checking agaisnt, so instead of iterating through a list of all enemies for a bullet collision, you are only checking against a handfull of closest enemies, and at whatever timesteps or intervals you feel work for you scope you update the tree to reflect the closest entities to your bullet/player at the current timestep.
Sorry if that seems a bit confusing but i only got a moment to write this out.
Basically you know what you gotta do and shouldn't worry about how many checks you are doing until you start to see a performance drop.
