- Basic complementary - Is using just accel and gyro in Attitude stabilized flight modes, and just gyro alone in Rate modes. Rattitude is Attitude that is changing to Rate at large deflection of the stick.
- INS13 - Is the fusion algorithm to use for full autonomous flight modes, this is the one that requires all sensors functional without exception. You can't use it indoors.
- There will always be a little bit of drift here and there due to imperfections of the build, external forces etc... but it should be possible to hover easily and it should stay 1-2s in place. If it's drifting too much that you can not control it or fly indoors, then some tuning discussed above is need.
If it's multi-rotor with propellers bigger than 5" you could try balancing them (unbalanced big props introduce vibrations). I feel big difference on 9" props whether they are balanced or not, with unbalanced completely unstable. You might also want to increase Accel and Gyro Tau (which is some sort of filtering), the higher you increase it I think the stronger the filtering, but it may help if you have a lot of vibrations, just don't overdo and try to keep it as close as possible to default if you don't see a difference when increasing it.
Fine tune your Board rotation (later if you decide to use external magnetometer you will need to account for these rotations on external mag as well, just keep that in mind, irrelevant now for Basic complementary). Finally if you are happy with it and there is almost no drift, tune the PIDs, try Autotune if you have F4 or F3 board, but check if PIDs are flyable and make sense, sometimes Autotune fails. If you have F1 (such as CC3D), you can't use Autotune due to RAM limitations, then use (recommended) Easytune is a bit longer than Autotune, but not as long as the standard Ziegler-Nichols method and Easytune works always.
What size of multi-rotor are you flying ? My gf would not allow anything bigger than 200 as well because of the furniture and walls